Hepatitis C Virus Inhibitors

ABSTRACT

The present disclosure relates to compounds, compositions and methods for the treatment of hepatitis C virus (HCV) infection. Also disclosed are pharmaceutical compositions containing such compounds and methods for using these compounds in the treatment of HCV infection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/167,989 filed Apr. 9, 2009.

FIELD OF THE DISCLOSURE

The present disclosure is generally directed to antiviral compounds, and more specifically directed to compounds which can inhibit the function of the NS5A protein encoded by Hepatitis C virus (HCV), compositions comprising such compounds, and methods for inhibiting the function of the NS5A protein.

BACKGROUND OF THE DISCLOSURE

HCV is a major human pathogen, infecting an estimated 170 million persons worldwide—roughly five times the number infected by human immunodeficiency virus type 1. A substantial fraction of these HCV infected individuals develop serious progressive liver disease, including cirrhosis and hepatocellular carcinoma.

The current standard of care for HCV, which employs a combination of pegylated-interferon and ribavirin, has a non-optimal success rate in achieving sustained viral response and causes numerous side effects. Thus, there is a clear and long-felt need to develop effective therapies to address this undermet medical need.

HCV is a positive-stranded RNA virus. Based on a comparison of the deduced amino acid sequence and the extensive similarity in the 5′ untranslated region, HCV has been classified as a separate genus in the Flaviviridae family. All members of the Flaviviridae family have enveloped virions that contain a positive stranded RNA genome encoding all known virus-specific proteins via translation of a single, uninterrupted, open reading frame.

Considerable heterogeneity is found within the nucleotide and encoded amino acid sequence throughout the HCV genome due to the high error rate of the encoded RNA dependent RNA polymerase which lacks a proof-reading capability. At least six major genotypes have been characterized, and more than 50 subtypes have been described with distribution worldwide. The clinical significance of the genetic heterogeneity of HCV has demonstrated a propensity for mutations to arise during monotherapy treatment, thus additional treatment options for use are desired. The possible modulator effect of genotypes on pathogenesis and therapy remains elusive.

The single strand HCV RNA genome is approximately 9500 nucleotides in length and has a single open reading frame (ORF) encoding a single large polyprotein of about 3000 amino acids. In infected cells, this polyprotein is cleaved at multiple sites by cellular and viral proteases to produce the structural and non-structural (NS) proteins. In the case of HCV, the generation of mature non-structural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B) is effected by two viral proteases. The first one is believed to be a metalloprotease and cleaves at the NS2-NS3 junction; the second one is a serine protease contained within the N-terminal region of NS3 (also referred to herein as NS3 protease) and mediates all the subsequent cleavages downstream of NS3, both in cis, at the NS3-NS4A cleavage site, and in trans, for the remaining NS4A-NS4B, NS4B-NS5A, NS5A-NS5B sites. The NS4A protein appears to serve multiple functions by both acting as a cofactor for the NS3 protease and assisting in the membrane localization of NS3 and other viral replicase components. The formation of a NS3-NS4A complex is necessary for proper protease activity resulting in increased proteolytic efficiency of the cleavage events. The NS3 protein also exhibits nucleoside triphosphatase and RNA helicase activities. NS5B (also referred to herein as HCV polymerase) is a RNA-dependent RNA polymerase that is involved in the replication of HCV with other HCV proteins, including NS5A, in a replicase complex.

Compounds useful for treating HCV-infected patients are desired which selectively inhibit HCV viral replication. In particular, compounds which are effective to inhibit the function of the NS5A protein are desired. The HCV NS5A protein is described, for example, in the following references: S. L. Tan, et al., Virology, 284:1-12 (2001); K.-J. Park, et al., J. Biol. Chem., 30711-30718 (2003); T. L. Tellinghuisen, et al., Nature, 435, 374 (2005); R. A. Love, et al., J. Virol, 83, 4395 (2009); N. Appel, et al., J. Biol. Chem., 281, 9833 (2006); L. Huang, J. Biol. Chem., 280, 36417 (2005); C. Rice, et al., WO2006093867.

In a first aspect the present disclosure provides a compound of Formula (I)

or a pharmaceutically acceptable salt thereof, wherein

L is selected from a bond,

R¹ and R² are

R¹ is

and

R² is selected from

wherein

denotes the point of attachment to the parent molecule;

R³ and R⁴ are independently selected from hydrogen and halo;

each R⁵ is independently selected from hydrogen and alkyl;

each R⁶ is independently selected from hydrogen and alkyl;

R^(6a) is hydrogen or alkyl, wherein the alkyl can optionally form a fused three-membered ring with an adjacent carbon atom;

each R⁷ is independently selected from hydrogen and —C(O)R⁸; and

each R⁸ is independently selected from alkoxy, alkyl, arylalkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, (NR^(c)R^(d))alkenyl, and (NR^(c)R^(d))alkyl.

In a first embodiment of the first aspect the present disclosure provides a compound of Formula (I), or a pharmaceutically acceptable salt thereof, wherein L is a bond. In a second embodiment of the first aspect, R¹ is

and

R² is selected from

In a third embodiment of the first aspect, R⁵ is hydrogen, R⁶ is methyl, and R^(6a) is alkyl, wherein the alkyl forms a fused three-membered ring with an adjacent carbon.

In a fourth embodiment of the first aspect the present disclosure provides a compound of Formula (I), or a pharmaceutically acceptable salt thereof, wherein L is a bond, R¹ and R² are each

each R⁵ is hydrogen, each R⁶ is methyl; and each R⁴ is chloro.

In a fifth embodiment of the first aspect the present disclosure provides a compound of Formula (I), or a pharmaceutically acceptable salt thereof, wherein L is a bond and R¹ and R² are each

In a sixth embodiment of the first aspect the present disclosure provides a compound of Formula (I), or a pharmaceutically acceptable salt thereof, wherein L is

In a seventh embodiment R¹ and R² are each

In an eighth embodiment, R⁵ is hydrogen and R⁶ is methyl.

In a second aspect the present disclosure provides a composition comprising a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier. In a first embodiment of the second aspect the composition further comprises one or two additional compounds having anti-HCV activity. In a second embodiment of the second aspect at least one of the additional compounds is an interferon or a ribavirin. In a third embodiment the interferon is selected from interferon alpha 2B, pegylated interferon alpha, consensus interferon, interferon alpha 2A, and lymphoblastoid interferon tau.

In a fourth embodiment of the second aspect the present disclosure provides a composition comprising a compound of Formula (I), or a pharmaceutically acceptable salt thereof, a pharmaceutically acceptable carrier, and one or two additional compounds having anti-HCV activity, wherein at least one of the additional compounds is selected from interleukin 2, interleukin 6, interleukin 12, a compound that enhances the development of a type 1 helper T cell response, interfering RNA, anti-sense RNA, Imiqimod, ribavirin, an inosine 5′-monophosphate dehydrogenase inhibitor, amantadine, and rimantadine.

In a fifth embodiment of the second aspect the present disclosure provides a composition comprising a compound of Formula (I), or a pharmaceutically acceptable salt thereof, a pharmaceutically acceptable carrier, and one or two additional compounds having anti-HCV activity, wherein at least one of the additional compounds is effective to inhibit the function of a target selected from HCV metalloprotease, HCV serine protease, HCV polymerase, HCV helicase, HCV NS4B protein, HCV entry, HCV assembly, HCV egress, HCV NS5A protein, and IMPDH for the treatment of an HCV infection.

In a third aspect the present disclosure provides a method of treating an HCV infection in a patient, comprising administering to the patient a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof. In a first embodiment of the third aspect the method further comprises administering one or two additional compounds having anti-HCV activity prior to, after or simultaneously with the compound of Formula (I), or a pharmaceutically acceptable salt thereof. In a second embodiment of the third aspect at least one of the additional compounds is an interferon or a ribavirin. In a third embodiment of the third aspect the interferon is selected from interferon alpha 2B, pegylated interferon alpha, consensus interferon, interferon alpha 2A, and lymphoblastoid interferon tau.

In a fourth embodiment of the third aspect the present disclosure provides a method of treating an HCV infection in a patient, comprising administering to the patient a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or two additional compounds having anti-HCV activity prior to, after or simultaneously with the compound of Formula (I), or a pharmaceutically acceptable salt thereof, wherein at least one of the additional compounds is selected from interleukin 2, interleukin 6, interleukin 12, a compound that enhances the development of a type 1 helper T cell response, interfering RNA, anti-sense RNA, Imiqimod, ribavirin, an inosine 5′-monophosphate dehydrogenase inhibitor, amantadine, and rimantadine.

In a fifth embodiment of the third aspect the present disclosure provides a method of treating an HCV infection in a patient, comprising administering to the patient a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or two additional compounds having anti-HCV activity prior to, after or simultaneously with the compound of Formula (I), or a pharmaceutically acceptable salt thereof, wherein at least one of the additional compounds is effective to inhibit the function of a target selected from HCV metalloprotease, HCV serine protease, HCV polymerase, HCV helicase, HCV NS4B protein, HCV entry, HCV assembly, HCV egress, HCV NS5A protein, and IMPDH for the treatment of an HCV infection.

Other embodiments of the present disclosure may comprise suitable combinations of two or more of embodiments and/or aspects disclosed herein.

Yet other embodiments and aspects of the disclosure will be apparent according to the description provided below.

The compounds of the present disclosure also exist as tautomers; therefore the present disclosure also encompasses all tautomeric forms.

The description of the present disclosure herein should be construed in congruity with the laws and principals of chemical bonding.

It should be understood that the compounds encompassed by the present disclosure are those that are suitably stable for use as pharmaceutical agent.

It is intended that the definition of any substituent or variable (e.g., R⁵, R⁶, and R⁷) at a particular location in a molecule be independent of its definitions elsewhere in that molecule.

All patents, patent applications, and literature references cited in the specification are herein incorporated by reference in their entirety. In the case of inconsistencies, the present disclosure, including definitions, will prevail.

As used in the present specification, the following terms have the meanings indicated:

As used herein, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise.

Unless stated otherwise, all aryl, cycloalkyl, and heterocyclyl groups of the present disclosure may be substituted as described in each of their respective definitions. For example, the aryl part of an arylalkyl group may be substituted as described in the definition of the term ‘aryl’.

The term “alkoxy,” as used herein, refers to an alkyl group attached to the parent molecular moiety through an oxygen atom.

The term “alkyl,” as used herein, refers to a group derived from a straight or branched chain saturated hydrocarbon containing from one to six carbon atoms. In the compounds of the present disclosure, when R^(6a) is alkyl, each alkyl can optionally form a fused three- to six-membered ring with an adjacent carbon atom to provide the structure shown below:

The term “aryl,” as used herein, refers to a phenyl group, or a bicyclic fused ring system wherein one or both of the rings is a phenyl group. Bicyclic fused ring systems consist of a phenyl group fused to a four- to six-membered aromatic or non-aromatic carbocyclic ring. The aryl groups of the present disclosure can be attached to the parent molecular moiety through any substitutable carbon atom in the group. Representative examples of aryl groups include, but are not limited to, indanyl, indenyl, naphthyl, phenyl, and tetrahydronaphthyl. The aryl groups of the present disclosure are optionally substituted with one, two, three, four, or five substituents independently selected from alkoxy, alkoxyalkyl, alkoxycarbonyl, alkyl, alkylcarbonyl, a second aryl group, arylalkoxy, arylalkyl, arylcarbonyl, cyano, halo, haloalkoxy, haloalkyl, heterocyclyl, heterocyclylalkyl, heterocyclylcarbonyl, hydroxy, hydroxyalkyl, nitro, —NR^(x)R^(y), (NR^(x)R^(y))alkyl, oxo, and —P(O)OR₂, wherein each R is independently selected from hydrogen and alkyl; and wherein the alkyl part of the arylalkyl and the heterocyclylalkyl are unsubstituted and wherein the second aryl group, the aryl part of the arylalkyl, the aryl part of the arylcarbonyl, the heterocyclyl, and the heterocyclyl part of the heterocyclylalkyl and the heterocyclylcarbonyl are further optionally substituted with one, two, or three substituents independently selected from alkoxy, alkyl, cyano, halo, haloalkoxy, haloalkyl, and nitro.

The term “arylalkyl,” as used herein, refers to an alkyl group substituted with one, two, or three aryl groups. The alkyl part of the arylalkyl is further optionally substituted with one or two additional groups independently selected from alkoxy, alkylcarbonyloxy, halo, haloalkoxy, haloalkyl, heterocyclyl, hydroxy, and —NR^(c)R^(d), wherein the heterocyclyl is further optionally substituted with one or two substituents independently selected from alkoxy, alkyl, unsubstituted aryl, unsubstituted arylalkoxy, unsubstituted arylalkoxycarbonyl, halo, haloalkoxy, haloalkyl, hydroxy, —NR^(x)R^(y), and oxo.

The term “cycloalkyl,” as used herein, refers to a saturated monocyclic, hydrocarbon ring system having three to seven carbon atoms and zero heteroatoms. Representative examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The cycloalkyl groups of the present disclosure are optionally substituted with one, two, three, four, or five substituents independently selected from alkoxy, alkyl, aryl, cyano, halo, haloalkoxy, haloalkyl, heterocyclyl, hydroxy, hydroxyalkyl, nitro, and —NR^(x)R^(y), wherein the aryl and the heterocyclyl are further optionally substituted with one, two, or three substituents independently selected from alkoxy, alkyl, cyano, halo, haloalkoxy, haloalkyl, hydroxy, and nitro.

The term “heterocyclyl,” as used herein, refers to a four-, five-, six-, or seven-membered ring containing one, two, three, or four heteroatoms independently selected from nitrogen, oxygen, and sulfur. The four-membered ring has zero double bonds, the five-membered ring has zero to two double bonds, and the six- and seven-membered rings have zero to three double bonds. The term “heterocyclyl” also includes bicyclic groups in which the heterocyclyl ring is fused to another monocyclic heterocyclyl group, or a four- to six-membered aromatic or non-aromatic carbocyclic ring; as well as bridged bicyclic groups such as 7-azabicyclo[2.2.1]hept-7-yl, 2-azabicyclo[2.2.2]oct-2-yl, and 2-azabicyclo[2.2.2]oct-3-yl. The heterocyclyl groups of the present disclosure can be attached to the parent molecular moiety through any carbon atom or nitrogen atom in the group. Examples of heterocyclyl groups include, but are not limited to, benzothienyl, furyl, imidazolyl, indolinyl, indolyl, isoquinolinyl, isothiazolyl, isoxazolyl, morpholinyl, oxazolyl, piperazinyl, piperidinyl, pyrazolyl, pyridinyl, pyrrolidinyl, pyrrolopyridinyl, pyrrolyl, quinolinyl, thiazolyl, thienyl, and thiomorpholinyl. The heterocyclyl groups of the present disclosure are optionally substituted with one, two, three, four, or five substituents independently selected from alkenyl, alkoxy, alkoxyalkyl, alkoxycarbonyl, alkyl, alkylcarbonyl, aryl, arylalkyl, arylcarbonyl, cyano, halo, haloalkoxy, haloalkyl, a second heterocyclyl group, heterocyclylalkyl, heterocyclylcarbonyl, hydroxy, hydroxyalkyl, nitro, —NR^(x)R^(y), (NR^(x)R^(y))alkyl, and oxo, wherein the alkyl part of the arylalkyl and the heterocyclylalkyl are unsubstituted and wherein the aryl, the aryl part of the arylalkyl, the aryl part of the arylcarbonyl, the second heterocyclyl group, and the heterocyclyl part of the heterocyclylalkyl and the heterocyclylcarbonyl are further optionally substituted with one, two, or three substituents independently selected from alkoxy, alkyl, cyano, halo, haloalkoxy, haloalkyl, and nitro.

The term “heterocyclylalkyl,” as used herein, refers to an alkyl group substituted with one, two, or three heterocyclyl groups. The alkyl part of the heterocyclylalkyl is further optionally substituted with one or two additional groups independently selected from alkoxy, alkylcarbonyloxy, aryl, halo, haloalkoxy, haloalkyl, hydroxy, and —NR^(c)R^(d), wherein the aryl is further optionally substituted with one or two substituents independently selected from alkoxy, alkyl, unsubstituted aryl, unsubstituted arylalkoxy, unsubstituted arylalkoxycarbonyl, halo, haloalkoxy, haloalkyl, hydroxy, and —R^(x)R^(y).

The term “—NR^(c)R^(d),” as used herein, refers to two groups, R^(c) and R^(d), which are attached to the parent molecular moiety through a nitrogen atom. R^(c) and R^(d) are independently selected from hydrogen, alkenyloxycarbonyl, alkoxyalkylcarbonyl, alkoxycarbonyl, alkyl, alkylcarbonyl, alkylsulfonyl, aryl, arylalkoxycarbonyl, arylalkyl, arylalkylcarbonyl, arylcarbonyl, aryloxycarbonyl, arylsulfonyl, cycloalkyl, cycloalkyloxycarbonyl, cycloalkylsulfonyl, formyl, haloalkoxycarbonyl, heterocyclyl, heterocyclylalkoxycarbonyl, heterocyclylalkyl, heterocyclylalkylcarbonyl, heterocyclylcarbonyl, heterocyclyloxycarbonyl, hydroxyalkylcarbonyl, (NR^(e)R^(f))alkyl, (NR^(e)R^(f))alkylcarbonyl, (NR^(e)R^(f))carbonyl, (NR^(e)R^(f))sulfonyl, —C(NCN)OR′, and —C(NCN)NR^(x)R^(y), wherein R′ is selected from alkyl and unsubstituted phenyl, and wherein the alkyl part of the arylalkyl, the arylalkylcarbonyl, the heterocyclylalkyl, and the heterocyclylalkylcarbonyl are further optionally substituted with one —NR^(e)R^(f) group; and wherein the aryl, the aryl part of the arylalkoxycarbonyl, the arylalkyl, the arylalkylcarbonyl, the arylcarbonyl, the aryloxycarbonyl, and the arylsulfonyl, the heterocyclyl, and the heterocyclyl part of the heterocyclylalkoxycarbonyl, the heterocyclylalkyl, the heterocyclylalkylcarbonyl, the heterocyclylcarbonyl, and the heterocyclyloxycarbonyl are further optionally substituted with one, two, or three substituents independently selected from alkoxy, alkyl, cyano, halo, haloalkoxy, haloalkyl, and nitro.

The term “(NR^(c)R^(d))alkenyl,” as used herein, refers to

wherein R^(c) and R^(d) are as defined herein and each R^(q) is independently hydrogen or C₁₋₃ alkyl.

The term “(NR^(c)R^(d))alkyl,” as used herein, refers to an alkyl group substituted with one or two —NR^(c)R^(d) groups. The alkyl part of the (NR^(c)R^(d))alkyl is further optionally substituted with one or two additional groups selected from alkoxy, alkoxyalkylcarbonyl, alkoxycarbonyl, alkylsulfanyl, arylalkoxycarbonyl, carboxy, cycloalkyl, heterocyclyl, heterocyclylcarbonyl, hydroxy, and (NR^(e)R^(f))carbonyl; wherein the heterocyclyl is further optionally substituted with one, two, three, four, or five substituents independently selected from alkoxy, alkyl, cyano, halo, haloalkoxy, haloalkyl, and nitro.

The term “—NR^(e)R^(f),” as used herein, refers to two groups, R^(e) and R^(f), which are attached to the parent molecular moiety through a nitrogen atom. R^(e) and R^(f) are independently selected from hydrogen, alkyl, unsubstituted aryl, unsubstituted arylalkyl, unsubstituted cycloalkyl, unsubstituted (cycloalkyl)alkyl, unsubstituted heterocyclyl, unsubstituted heterocyclylalkyl, (NR^(x)R^(y))alkyl, and (NR^(x)R^(y))carbonyl.

The term “—NR^(x)R^(y),” as used herein, refers to two groups, Rx and R^(y), which are attached to the parent molecular moiety through a nitrogen atom. R^(x) and R^(y) are independently selected from hydrogen, alkoxycarbonyl, alkyl, alkylcarbonyl, unsubstituted aryl, unsubstituted arylalkoxycarbonyl, unsubstituted arylalkyl, unsubstituted cycloalkyl, unsubstituted heterocyclyl, and (NR^(x′)R^(y′))carbonyl, wherein R^(x′) and R^(y′) are independently selected from hydrogen and alkyl.

Asymmetric centers exist in the compounds of the present disclosure. These centers are designated by the symbols “R” or “S”, depending on the configuration of substituents around the chiral carbon atom. It should be understood that the disclosure encompasses all stereochemical isomeric forms, or mixtures thereof, which possess the ability to inhibit NS5A. Individual stereoisomers of compounds can be prepared synthetically from commercially available starting materials which contain chiral centers or by preparation of mixtures of enantiomeric products followed by separation such as conversion to a mixture of diastereomers followed by separation or recrystallization, chromatographic techniques, or direct separation of enantiomers on chiral chromatographic columns. Starting compounds of particular stereochemistry are either commercially available or can be made and resolved by techniques known in the art.

Certain compounds of the present disclosure may also exist in different stable conformational forms which may be separable. Torsional asymmetry due to restricted rotation about an asymmetric single bond, for example because of steric hindrance or ring strain, may permit separation of different conformers. The present disclosure includes each conformational isomer of these compounds and mixtures thereof.

The term “compounds of the present disclosure”, and equivalent expressions, are meant to embrace compounds of Formula (I), and pharmaceutically acceptable enantiomers, diastereomers, and salts thereof. Similarly, references to intermediates are meant to embrace their salts where the context so permits.

The present disclosure is intended to include all isotopes of atoms occurring in the present compounds. Isotopes include those atoms having the same atomic number but different mass numbers. By way of general example and without limitation, isotopes of hydrogen include deuterium and tritium. Isotopes of carbon include ¹³C and ¹⁴C. Isotopically-labeled compounds of the invention can generally be prepared by conventional techniques known to those skilled in the art or by processes analogous to those described herein, using an appropriate isotopically-labeled reagent in place of the non-labeled reagent otherwise employed. Such compounds may have a variety of potential uses, for example as standards and reagents in determining biological activity. In the case of stable isotopes, such compounds may have the potential to favorably modify biological, pharmacological, or pharmacokinetic properties.

The compounds of the present disclosure can exist as pharmaceutically acceptable salts. The term “pharmaceutically acceptable salt,” as used herein, represents salts or zwitterionic forms of the compounds of the present disclosure which are water or oil-soluble or dispersible, which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of patients without excessive toxicity, irritation, allergic response, or other problem or complication commensurate with a reasonable benefit/risk ratio, and are effective for their intended use. The salts can be prepared during the final isolation and purification of the compounds or separately by reacting a suitable nitrogen atom with a suitable acid. Representative acid addition salts include acetate, adipate, alginate, citrate, aspartate, benzoate, benzenesulfonate, bisulfate, butyrate, camphorate, camphorsulfonate; digluconate, dihydrobromide, dihydrochloride, dihydroiodide, glycerophosphate, hemisulfate, heptanoate, hexanoate, formate, fumarate, hydrochloride, hydrobromide, hydroiodide, 2-hydroxyethanesulfonate, lactate, maleate, mesitylenesulfonate, methanesulfonate, naphthalenesulfonate, nicotinate, 2-naphthalenesulfonate, oxalate, palmoate, pectinate, persulfate, 3-phenylpropionate, picrate, pivalate, propionate, succinate, tartrate, trichloroacetate, trifluoroacetate, phosphate, glutamate, bicarbonate, para-toluenesulfonate, and undecanoate. Examples of acids which can be employed to form pharmaceutically acceptable addition salts include inorganic acids such as hydrochloric, hydrobromic, sulfuric, and phosphoric, and organic acids such as oxalic, maleic, succinic, and citric.

Basic addition salts can be prepared during the final isolation and purification of the compounds by reacting a carboxy group with a suitable base such as the hydroxide, carbonate, or bicarbonate of a metal cation or with ammonia or an organic primary, secondary, or tertiary amine. The cations of pharmaceutically acceptable salts include lithium, sodium, potassium, calcium, magnesium, and aluminum, as well as nontoxic quaternary amine cations such as ammonium, tetramethylammonium, tetraethylammonium, methylamine, dimethylamine, trimethylamine, triethylamine, diethylamine, ethylamine, tributylamine, pyridine, N,N-dimethylaniline, N-methylpiperidine, N-methylmorpholine, dicyclohexylamine, procaine, dibenzylamine, N,N-dibenzylphenethylamine, and N,N′-dibenzylethylenediamine. Other representative organic amines useful for the formation of base addition salts include ethylenediamine, ethanolamine, diethanolamine, piperidine, and piperazine.

When it is possible that, for use in therapy, therapeutically effective amounts of a compound of formula (I), as well as pharmaceutically acceptable salts thereof, may be administered as the raw chemical, it is possible to present the active ingredient as a pharmaceutical composition. Accordingly, the disclosure further provides pharmaceutical compositions, which include therapeutically effective amounts of compounds of formula (I) or pharmaceutically acceptable salts thereof, and one or more pharmaceutically acceptable carriers, diluents, or excipients. The term “therapeutically effective amount,” as used herein, refers to the total amount of each active component that is sufficient to show a meaningful patient benefit, e.g., a reduction in viral load. When applied to an individual active ingredient, administered alone, the term refers to that ingredient alone. When applied to a combination, the term refers to combined amounts of the active ingredients that result in the therapeutic effect, whether administered in combination, serially, or simultaneously. The compounds of formula (I) and pharmaceutically acceptable salts thereof, are as described above. The carrier(s), diluent(s), or excipient(s) must be acceptable in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof. In accordance with another aspect of the present disclosure there is also provided a process for the preparation of a pharmaceutical formulation including admixing a compound of formula (I), or a pharmaceutically acceptable salt thereof, with one or more pharmaceutically acceptable carriers, diluents, or excipients. The term “pharmaceutically acceptable,” as used herein, refers to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of patients without excessive toxicity, irritation, allergic response, or other problem or complication commensurate with a reasonable benefit/risk ratio, and are effective for their intended use.

Pharmaceutical formulations may be presented in unit dose forms containing a predetermined amount of active ingredient per unit dose. Dosage levels of between about 0.01 and about 250 milligram per kilogram (“mg/kg”) body weight per day, preferably between about 0.05 and about 100 mg/kg body weight per day of the compounds of the present disclosure are typical in a monotherapy for the prevention and treatment of HCV mediated disease. Typically, the pharmaceutical compositions of this disclosure will be administered from about 1 to about 5 times per day or alternatively, as a continuous infusion. Such administration can be used as a chronic or acute therapy. The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending on the condition being treated, the severity of the condition, the time of administration, the route of administration, the rate of excretion of the compound employed, the duration of treatment, and the age, gender, weight, and condition of the patient. Preferred unit dosage formulations are those containing a daily dose or sub-dose, as herein above recited, or an appropriate fraction thereof, of an active ingredient. Treatment may be initiated with small dosages substantially less than the optimum dose of the compound. Thereafter, the dosage is increased by small increments until the optimum effect under the circumstances is reached. In general, the compound is most desirably administered at a concentration level that will generally afford antivirally effective results without causing any harmful or deleterious side effects.

When the compositions of this disclosure comprise a combination of a compound of the present disclosure and one or more additional therapeutic or prophylactic agent, both the compound and the additional agent are usually present at dosage levels of between about 10 to 150%, and more preferably between about 10 and 80% of the dosage normally administered in a monotherapy regimen.

Pharmaceutical formulations may be adapted for administration by any appropriate route, for example by the oral (including buccal or sublingual), rectal, nasal, topical (including buccal, sublingual, or transdermal), vaginal, or parenteral (including subcutaneous, intracutaneous, intramuscular, intra-articular, intrasynovial, intrasternal, intrathecal, intralesional, intravenous, or intradermal injections or infusions) route. Such formulations may be prepared by any method known in the art of pharmacy, for example by bringing into association the active ingredient with the carrier(s) or excipient(s). Oral administration or administration by injection are preferred.

Pharmaceutical formulations adapted for oral administration may be presented as discrete units such as capsules or tablets; powders or granules; solutions or suspensions in aqueous or non-aqueous liquids; edible foams or whips; or oil-in-water liquid emulsions or water-in-oil emulsions.

For instance, for oral administration in the form of a tablet or capsule, the active drug component can be combined with an oral, non-toxic pharmaceutically acceptable inert carrier such as ethanol, glycerol, water, and the like. Powders are prepared by comminuting the compound to a suitable fine size and mixing with a similarly comminuted pharmaceutical carrier such as an edible carbohydrate, as, for example, starch or mannitol. Flavoring, preservative, dispersing, and coloring agent can also be present.

Capsules are made by preparing a powder mixture, as described above, and filling formed gelatin sheaths. Glidants and lubricants such as colloidal silica, talc, magnesium stearate, calcium stearate, or solid polyethylene glycol can be added to the powder mixture before the filling operation. A disintegrating or solubilizing agent such as agar-agar, calcium carbonate, or sodium carbonate can also be added to improve the availability of the medicament when the capsule is ingested.

Moreover, when desired or necessary, suitable binders, lubricants, disintegrating agents, and coloring agents can also be incorporated into the mixture. Suitable binders include starch, gelatin, natural sugars such as glucose or beta-lactose, corn sweeteners, natural and synthetic gums such as acacia, tragacanth or sodium alginate, carboxymethylcellulose, polyethylene glycol, and the like. Lubricants used in these dosage forms include sodium oleate, sodium chloride, and the like. Disintegrators include, without limitation, starch, methyl cellulose, agar, betonite, xanthan gum, and the like. Tablets are formulated, for example, by preparing a powder mixture, granulating or slugging, adding a lubricant and disintegrant, and pressing into tablets. A powder mixture is prepared by mixing the compound, suitable comminuted, with a diluent or base as described above, and optionally, with a binder such as carboxymethylcellulose, an aliginate, gelating, or polyvinyl pyrrolidone, a solution retardant such as paraffin, a resorption accelerator such as a quaternary salt and/or and absorption agent such as betonite, kaolin, or dicalcium phosphate. The powder mixture can be granulated by wetting with a binder such as syrup, starch paste, acadia mucilage, or solutions of cellulosic or polymeric materials and forcing through a screen. As an alternative to granulating, the powder mixture can be run through the tablet machine and the result is imperfectly formed slugs broken into granules. The granules can be lubricated to prevent sticking to the tablet forming dies by means of the addition of stearic acid, a stearate salt, talc, or mineral oil. The lubricated mixture is then compressed into tablets. The compounds of the present disclosure can also be combined with a free flowing inert carrier and compressed into tablets directly without going through the granulating or slugging steps. A clear or opaque protective coating consisting of a sealing coat of shellac, a coating of sugar or polymeric material, and a polish coating of wax can be provided. Dyestuffs can be added to these coatings to distinguish different unit dosages.

Oral fluids such as solution, syrups, and elixirs can be prepared in dosage unit form so that a given quantity contains a predetermined amount of the compound. Syrups can be prepared by dissolving the compound in a suitably flavored aqueous solution, while elixirs are prepared through the use of a non-toxic vehicle. Solubilizers and emulsifiers such as ethoxylated isostearyl alcohols and polyoxyethylene sorbitol ethers, preservatives, flavor additive such as peppermint oil or natural sweeteners, or saccharin or other artificial sweeteners, and the like can also be added.

Where appropriate, dosage unit formulations for oral administration can be microencapsulated. The formulation can also be prepared to prolong or sustain the release as for example by coating or embedding particulate material in polymers, wax, or the like.

The compounds of formula (I), and pharmaceutically acceptable salts thereof, can also be administered in the form of liposome delivery systems, such as small unilamellar vesicles, large unilamellar vesicles, and multilamellar vesicles. Liposomes can be formed from a variety of phospholipids, such as cholesterol, stearylamine, or phophatidylcholines.

The compounds of formula (I) and pharmaceutically acceptable salts thereof may also be delivered by the use of monoclonal antibodies as individual carriers to which the compound molecules are coupled. The compounds may also be coupled with soluble polymers as targetable drug carriers. Such polymers can include polyvinylpyrrolidone, pyran copolymer, polyhydroxypropylmethacrylamidephenol, polyhydroxyethylaspartamidephenol, or polyethyleneoxidepolylysine substituted with palmitoyl residues. Furthermore, the compounds may be coupled to a class of biodegradable polymers useful in achieving controlled release of a drug, for example, polylactic acid, polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters, polyacetals, polydihydropyrans, polycyanoacrylates, and cross-linked or amphipathic block copolymers of hydrogels.

Pharmaceutical formulations adapted for transdermal administration may be presented as discrete patches intended to remain in intimate contact with the epidermis of the recipient for a prolonged period of time. For example, the active ingredient may be delivered from the patch by iontophoresis as generally described in Pharmaceutical Research 1986, 3(6), 318.

Pharmaceutical formulations adapted for topical administration may be formulated as ointments, creams, suspensions, lotions, powders, solutions, pastes, gels, sprays, aerosols, or oils.

Pharmaceutical formulations adapted for rectal administration may be presented as suppositories or as enemas.

Pharmaceutical formulations adapted for nasal administration wherein the carrier is a solid include a course powder having a particle size for example in the range 20 to 500 microns which is administered in the manner in which snuff is taken, i.e., by rapid inhalation through the nasal passage from a container of the powder held close up to the nose. Suitable formulations wherein the carrier is a liquid, for administration as a nasal spray or nasal drops, include aqueous or oil solutions of the active ingredient.

Pharmaceutical formulations adapted for administration by inhalation include fine particle dusts or mists, which may be generated by means of various types of metered, dose pressurized aerosols, nebulizers, or insufflators.

Pharmaceutical formulations adapted for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams, or spray formulations.

Pharmaceutical formulations adapted for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteriostats, and soutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example sealed ampoules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules, and tablets.

It should be understood that in addition to the ingredients particularly mentioned above, the formulations may include other agents conventional in the art having regard to the type of formulation in question, for example those suitable for oral administration may include flavoring agents.

The term “patient” includes both human and other mammals.

The term “treating” refers to: (i) preventing a disease, disorder or condition from occurring in a patient that may be predisposed to the disease, disorder, and/or condition but has not yet been diagnosed as having it; (ii) inhibiting the disease, disorder, or condition, i.e., arresting its development; and (iii) relieving the disease, disorder, or condition, i.e., causing regression of the disease, disorder, and/or condition.

The compounds of the present disclosure can also be administered with a cyclosporin, for example, cyclosporin A. Cyclosporin A has been shown to be active against HCV in clinical trials (Hepatology 2003, 38, 1282; Biochem. Biophys. Res. Commun. 2004, 313, 42; J. Gastroenterol. 2003, 38, 567).

Table 1 below lists some illustrative examples of compounds that can be administered with the compounds of this disclosure. The compounds of the disclosure can be administered with other anti-HCV active compounds in combination therapy, either jointly or separately, or by combining the compounds into a composition.

TABLE 1 Physiological Type of Inhibitor or Brand Name Class Target Source Company NIM811 Cyclophilin Novartis Inhibitor Zadaxin Immuno-modulator Sciclone Suvus Methylene blue Bioenvision Actilon TLR9 agonist Coley (CPG10101) Batabulin (T67) Anticancer β-tubulin inhibitor Tularik Inc., South San Francisco, CA ISIS 14803 Antiviral antisense ISIS Pharmaceuticals Inc, Carlsbad, CA/Elan Phamaceuticals Inc., New York, NY Summetrel Antiviral antiviral Endo Pharmaceuticals Holdings Inc., Chadds Ford, PA GS-9132 (ACH- Antiviral HCV Inhibitor Achillion/Gilead 806) Pyrazolopyrimidine Antiviral HCV Inhibitors Arrow compounds and Therapeutics Ltd. salts From WO- 2005047288 26 May 2005 Levovirin Antiviral IMPDH inhibitor Ribapharm Inc., Costa Mesa, CA Merimepodib Antiviral IMPDH inhibitor Vertex (VX-497) Pharmaceuticals Inc., Cambridge, MA XTL-6865 (XTL- Antiviral monoclonal XTL 002) antibody Biopharmaceuticals Ltd., Rehovot, Isreal Telaprevir Antiviral NS3 serine protease Vertex (VX-950, LY- inhibitor Pharmaceuticals 570310) Inc., Cambridge, MA/Eli Lilly and Co. Inc., Indianapolis, IN HCV-796 Antiviral NS5B Replicase Wyeth/ Inhibitor Viropharma NM-283 Antiviral NS5B Replicase Idenix/Novartis Inhibitor GL-59728 Antiviral NS5B Replicase Gene Labs/ Inhibitor Novartis GL-60667 Antiviral NS5B Replicase Gene Labs/ Inhibitor Novartis 2′C MeA Antiviral NS5B Replicase Gilead Inhibitor PSI 6130 Antiviral NS5B Replicase Roche Inhibitor R1626 Antiviral NS5B Replicase Roche Inhibitor 2′C Methyl Antiviral NS5B Replicase Merck adenosine Inhibitor JTK-003 Antiviral RdRp inhibitor Japan Tobacco Inc., Tokyo, Japan Levovirin Antiviral ribavirin ICN Pharmaceuticals, Costa Mesa, CA Ribavirin Antiviral ribavirin Schering-Plough Corporation, Kenilworth, NJ Viramidine Antiviral Ribavirin Prodrug Ribapharm Inc., Costa Mesa, CA Heptazyme Antiviral ribozyme Ribozyme Pharmaceuticals Inc., Boulder, CO BILN-2061 Antiviral serine protease Boehringer inhibitor Ingelheim Pharma KG, Ingelheim, Germany SCH 503034 Antiviral serine protease Schering Plough inhibitor Zadazim Immune modulator Immune modulator SciClone Pharmaceuticals Inc., San Mateo, CA Ceplene Immunomodulator immune modulator Maxim Pharmaceuticals Inc., San Diego, CA CellCept Immunosuppressant HCV IgG immuno- F. Hoffmann-La suppressant Roche LTD, Basel, Switzerland Civacir Immunosuppressant HCV IgG immuno- Nabi suppressant Biopharmaceuticals Inc., Boca Raton, FL Albuferon-α Interferon albumin IFN-α2b Human Genome Sciences Inc., Rockville, MD Infergen A Interferon IFN InterMune alfacon-1 Pharmaceuticals Inc., Brisbane, CA Omega IFN Interferon IFN-ω Intarcia Therapeutics IFN-β and Interferon IFN-β and EMZ701 Transition EMZ701 Therapeutics Inc., Ontario, Canada Rebif Interferon IFN-β1a Serono, Geneva, Switzerland Roferon A Interferon IFN-α2a F. Hoffmann-La Roche LTD, Basel, Switzerland Intron A Interferon IFN-α2b Schering-Plough Corporation, Kenilworth, NJ Intron A and Interferon IFN-α2b/α1- RegeneRx Zadaxin thymosin Biopharma. Inc., Bethesda, MD/ SciClone Pharmaceuticals Inc, San Mateo, CA Rebetron Interferon IFN-α2b/ribavirin Schering-Plough Corporation, Kenilworth, NJ Actimmune Interferon INF-γ InterMune Inc., Brisbane, CA Interferon-β Interferon Interferon-β-1a Serono Multiferon Interferon Long lasting IFN Viragen/ Valentis Wellferon Interferon Lympho-blastoid GlaxoSmithKline IFN-αn1 plc, Uxbridge, UK Omniferon Interferon natural IFN-α Viragen Inc., Plantation, FL Pegasys Interferon PEGylated IFN-α2a F. Hoffmann-La Roche LTD, Basel, Switzerland Pegasys and Interferon PEGylated IFN- Maxim Ceplene α2a/ Pharmaceuticals immune modulator Inc., San Diego, CA Pegasys and Interferon PEGylated IFN- F. Hoffmann-La Ribavirin α2a/ribavirin Roche LTD, Basel, Switzerland PEG-Intron Interferon PEGylated IFN-α2b Schering-Plough Corporation, Kenilworth, NJ PEG-Intron/ Interferon PEGylated IFN- Schering-Plough Ribavirin α2b/ribavirin Corporation, Kenilworth, NJ IP-501 Liver protection antifibrotic Indevus Pharmaceuticals Inc., Lexington, MA IDN-6556 Liver protection caspase inhibitor Idun Pharmaceuticals Inc., San Diego, CA ITMN-191 (R- Antiviral serine protease InterMune 7227) inhibitor Pharmaceuticals Inc., Brisbane, CA GL-59728 Antiviral NS5B Replicase Genelabs Inhibitor ANA-971 Antiviral TLR-7 agonist Anadys Boceprevir Antiviral serine protease Schering Plough inhibitor TMS-435 Antiviral serine protease Tibotec BVBA, inhibitor Mechelen, Belgium BI-201335 Antiviral serine protease Boehringer inhibitor Ingelheim Pharma KG, Ingelheim, Germany MK-7009 Antiviral serine protease Merck inhibitor PF-00868554 Antiviral replicase inhibitor Pfizer ANA598 Antiviral Non-Nucleoside Anadys NS5B Polymerase Pharmaceuticals, Inhibitor Inc., San Diego, CA, USA IDX375 Antiviral Non-Nucleoside Idenix Replicase Inhibitor Pharmaceuticals, Cambridge, MA, USA BILB 1941 Antiviral NS5B Polymerase Boehringer Inhibitor Ingelheim Canada Ltd R&D, Laval, QC, Canada PSI-7851 Antiviral Nucleoside Pharmasset, Polymerase Princeton, NJ, inhibitor USA VCH-759 Antiviral NS5B Polymerase ViroChem Pharma Inhibitor VCH-916 Antiviral NS5B Polymerase ViroChem Pharma Inhibitor GS-9190 Antiviral NS5B Polymerase Gilead Inhibitor Peg-interferon Antiviral Interferon ZymoGenetics/Bristol- lamda Myers Squibb

The compounds of the present disclosure may also be used as laboratory reagents. Compounds may be instrumental in providing research tools for designing of viral replication assays, validation of animal assay systems and structural biology studies to further enhance knowledge of the HCV disease mechanisms. Further, the compounds of the present disclosure are useful in establishing or determining the binding site of other antiviral compounds, for example, by competitive inhibition.

The compounds of this disclosure may also be used to treat or prevent viral contamination of materials and therefore reduce the risk of viral infection of to laboratory or medical personnel or patients who come in contact with such materials, e.g., blood, tissue, surgical instruments and garments, laboratory instruments and garments, and blood collection or transfusion apparatuses and materials.

This disclosure is intended to encompass compounds having formula (I) when prepared by synthetic processes or by metabolic processes including those occurring in the human or animal body (in vivo) or processes occurring in vitro.

The abbreviations used in the present application, including particularly in the illustrative schemes and examples which follow, are well-known to those skilled in the art. Some of the abbreviations used are as follows: min for minutes; TFA for trifluoroacetic acid; DMAP for N,N-dimethylaminopyridine; Boc or BOC for tert-butoxycarbonyl; EtOAc for ethyl acetate; DMF for N,N-dimethylformamide; DIEA for diisopropylethylamine; MeOH for methanol; HATU for O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate; Ph for phenyl; h for hours; THF for tetrahydrofuran; SEM for 2-trimethylsilylethoxymethoxy; Cbz for carbonylbenzyloxy; dppf for diphenylphosphinoferrocene; EtOH for ethanol; RT for room temperature or retention time (context will dictate); and R_(t) for retention time.

The compounds and processes of the present disclosure will be better understood in connection with the following synthetic schemes which illustrate the methods by which the compounds of the present disclosure may be prepared. Starting materials can be obtained from commercial sources or prepared by well-established literature methods known to those of ordinary skill in the art. It will be readily apparent to one of ordinary skill in the art that the compounds defined above can be synthesized by substitution of the appropriate reactants and agents in the syntheses shown below. It will also be readily apparent to one skilled in the art that the selective protection and deprotection steps, as well as the order of the steps themselves, can be carried out in varying order, depending on the nature of the variables to successfully complete the syntheses below. The variables are as defined above unless otherwise noted below.

Scheme 1 Substituted Phenylglycine Derivatives

Substituted phenylglycine derivatives can be prepared by a number of methods shown below. Phenylglycine t-butyl ester can be reductively alkylated (pathway A) with an appropriate aldehyde and a reductant such as sodium cyanoborohydride in acidic medium. Hydrolysis of the t-butyl ester can be accomplished with strong acid such as HCl or trifluoroacetic acid. Alternatively, phenylglycine can be alkylated with an alkyl halide such as ethyl iodide and a base such as sodium bicarbonate or potassium carbonate (pathway B). Pathway C illustrates reductive alkylation of phenylglycine as in pathway A followed by a second reductive alkylation with an alternate aldehyde such as formaldehyde in the presence of a reducing agent and acid. Pathway D illustrates the synthesis of substituted phenylglycines via the corresponding mandelic acid analogs. Conversion of the secondary alcohol to a competent leaving group can be accomplished with p-toluenesulfonyl chloride. Displacement of the tosylate group with an appropriate amine followed by reductive removal of the benzyl ester can provide substituted phenylglycine derivatives. In pathway E a racemic substituted phenylglycine derivative is resolved by esterification with an enantiomerically pure chiral auxiliary such as but not limited to (+)-1-phenylethanol, (−)-1-phenylethanol, an Evan's oxazolidinone, or enantiomerically pure pantolactone. Separation of the diastereomers is accomplished via chromatography (silica gel, HPLC, crystallization, etc) followed by removal of the chiral auxiliary providing enantiomerically pure phenylglycine derivatives. Pathway H illustrates a synthetic sequence which intersects with pathway E wherein the aforementioned chiral auxiliary is installed prior to amine addition. Alternatively, an ester of an arylacetic acid can be brominated with a source of bromonium ion such as bromine, N-bromosuccinimide, or CBr₄. The resultant benzylic bromide can be displaced with a variety of mono- or disubstituted amines in the presence of a tertiary amine base such as triethylamine or Hunig's base. Hydrolysis of the methyl ester via treatment with lithium hydroxide at low temperature or 6N HCl at elevated temperature provides the substituted phenylglycine derivatives. Another method is shown in pathway G. Glycine analogs can be derivatized with a variety of aryl halides in the presence of a source of palladium (0) such as palladium bis(tributylphosphine) and base such as potassium phosphate. The resultant ester can then be hydrolyzed by treatment with base or acid. It should be understood that other well known methods to prepare phenylglycine derivatives exist in the art and can be amended to provide the desired compounds in this description. It should also be understood that the final phenylglycine derivatives can be purified to enantiomeric purity greater than 98% ee via preparative HPLC.

In another embodiment of the present disclosure, acylated phenylglycine derivatives may be prepared as illustrated below. Phenylglycine derivatives wherein the carboxylic acid is protected as an easily removed ester, may be acylated with an acid chloride in the presence of a base such as triethylamine to provide the corresponding amides (pathway A). Pathway B illustrates the acylation of the starting phenylglycine derivative with an appropriate chloroformate while pathway C shows reaction with an appropriate isocyanate or carbamoyl chloride. Each of the three intermediates shown in pathways A-C may be deprotected by methods known by those skilled in the art (ie; treatment of the t-butyl ester with strong base such as HCl or trifluoroacetic acid).

Amino-substituted phenylacetic acids may be prepared by treatment of a chloromethylphenylacetic acid with an excess of an amine.

Synthesis of Common Acid Precursors

Purity assessment and low resolution mass analysis were conducted on a Shimadzu LC system coupled with Waters Micromass ZQ MS system. It should be noted that retention times may vary slightly between machines. LC conditions applicable to the current section, unless noted otherwise.

Cond.-MS-W1 Column ═XTERRA 3.0×50 mm S7 Start % B=0 Final % B=100

Gradient time=2 min Stop time=3 min Flow Rate=5 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Cond.-MS-W2 Column ═XTERRA 3.0×50 mm S7 Start % B=0 Final % B=100

Gradient time=3 min Stop time=4 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Cond.-MS-W5 Column ═XTERRA 3.0×50 mm S7 Start % B=0 Final % B=30

Gradient time=2 min Stop time=3 min Flow Rate=5 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Cond.-D1 Column ═XTERRA C18 3.0×50 mm S7 Start % B=0 Final % B=100

Gradient time=3 min Stop time=4 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Cond.-D2 Column=Phenomenex-Luna 4.6×50 mm 510 Start % B=0 Final % B=100

Gradient time=3 min Stop time=4 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Cond.-M3 Column ═XTERRA C18 3.0×50 mm S7 Start % B=0 Final % B=40

Gradient time=2 min Stop time=3 min Flow Rate=5 ml/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Condition I Column=Phenomenex-Luna 3.0×50 mm S10 Start % B=0 Final % B=100

Gradient time=2 min Stop time=3 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Condition II Column=Phenomenex-Luna 4.6×50 mm S10 Start % B=0 Final % B=100

Gradient time=2 min Stop time=3 min Flow Rate=5 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Condition III Column ═XTERRA C18 3.0×50 mm S7 Start % B=0 Final % B=100

Gradient time=3 min Stop time=4 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

A suspension of 10% Pd/C (2.0 g) in methanol (10 mL) was added to a mixture of (R)-2-phenylglycine (10 g, 66.2 mmol), formaldehyde (33 mL of 37% wt. in water), 1N HCl (30 mL) and methanol (30 mL), and exposed to H₂ (60 psi) for 3 hours. The reaction mixture was filtered through diatomaceous earth (Celite®), and the filtrate was concentrated in vacuo. The resulting crude material was recrystallized from isopropanol to provide the HCl salt of Cap-1 as a white needle (4.0 g). Optical rotation: −117.1° [c=9.95 mg/mL in H₂O; λ=589 nm]. ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): δ 7.43-7.34 (m, 5H), 4.14 (s, 1H), 2.43 (s, 6H); LC (Cond. I): RT=0.25; LC/MS: Anal. Calcd. for [M+H]⁺C₁₀H₁₄NO₂ 180.10. found 180.17; HRMS: Anal. Calcd. for [M+H]⁺C₁₀H₁₄NO₂ 180.1025. found 180.1017.

NaBH₃CN (6.22 g, 94 mmol) was added in portions over a few minutes to a cooled (ice/water) mixture of (R)-2-Phenylglycine (6.02 g, 39.8 mmol) and methanol (100 mL), and stirred for 5 minutes. Acetaldehyde (10 mL) was added dropwise over 10 minutes and stirring was continued at the same cooled temperature for 45 minutes and at ambient temperature for ˜6.5 hours. The reaction mixture was cooled back with ice-water bath, treated with water (3 mL) and then quenched with a dropwise addition of concentrated HCl over ˜45 minutes until the pH of the mixture was 1.5-2.0. The cooling bath was removed and the stirring was continued while adding concentrated HCl in order to maintain the pH of the mixture around 1.5-2.0. The reaction mixture was stirred overnight, filtered to remove the white suspension, and the filtrate was concentrated in vacuo. The crude material was recrystallized from ethanol to afford the HCl salt of Cap-2 as a shining white solid in two crops (crop-1: 4.16 g; crop-2: 2.19 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): 10.44 (1.00, br s, 1H), 7.66 (m, 2H), 7.51 (m, 3H), 5.30 (s, 1H), 3.15 (br m, 2H), 2.98 (br m, 2H), 1.20 (app br s, 6H). Crop-1: [α]²⁵-102.21° (c=0.357, H₂O); crop-2: [α]²⁵-99.7° (c=0.357, H₂O). LC (Cond. I): RT=0.43 min; LC/MS: Anal. Calcd. for [M+H]⁺ C₁₂H₁₈NO₂: 208.13. found 208.26.

Acetaldehyde (5.0 mL, 89.1 mmol) and a suspension of 10% Pd/C (720 mg) in methanol/H₂O (4 mL/1 mL) was sequentially added to a cooled (˜15° C.) mixture of (R)-2-phenylglycine (3.096 g, 20.48 mmol), 1N HCl (30 mL) and methanol (40 mL). The cooling bath was removed and the reaction mixture was stirred under a balloon of H₂ for 17 hours. An additional acetaldehyde (10 mL, 178.2 mmol) was added and stirring continued under H₂ atmosphere for 24 hours [Note: the supply of H₂ was replenished as needed throughout the reaction]. The reaction mixture was filtered through diatomaceous earth (Celite®), and the filtrate was concentrated in vacuo. The resulting crude material was recrystallized from isopropanol to provide the HCl salt of (R)-2-(ethylamino)-2-phenylacetic acid as a shining white solid (2.846 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 14.15 (br s, 1H), 9.55 (br s, 2H), 7.55-7.48 (m, 5H), 2.88 (br m, 1H), 2.73 (br m, 1H), 1.20 (app t, J=7.2, 3H). LC (Cond. I): RT=0.39 min; >95% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₁₀H₁₄NO₂: 180.10. found 180.18.

A suspension of 10% Pd/C (536 mg) in methanol/H₂O (3 mL/1 mL) was added to a mixture of (R)-2-(ethylamino)-2-phenylacetic acid/HCl (1.492 g, 6.918 mmol), formaldehyde (20 mL of 37% wt. in water), 1N HCl (20 mL) and methanol (23 mL). The reaction mixture was stirred under a balloon of H₂ for ˜72 hours, where the H₂ supply was replenished as needed. The reaction mixture was filtered through diatomaceous earth (Celite®) and the filtrate was concentrated in vacuo. The resulting crude material was recrystallized from isopropanol (50 mL) to provide the HCl salt of Cap-3 as a white solid (985 mg). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 10.48 (br s, 1H), 7.59-7.51 (m, 5H), 5.26 (s, 1H), 3.08 (app br s, 2H), 2.65 (br s, 3H), 1.24 (br m, 3H). LC (Cond. I): RT=0.39 min; >95% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₁₁H₁₆NO₂: 194.12. found 194.18; HRMS: Anal. Calcd. for [M+H]⁺C₁₁H₁₆NO₂: 194.1180. found 194.1181.

ClCO₂Me (3.2 mL, 41.4 mmol) was added dropwise to a cooled (ice/water) THF (410 mL) semi-solution of (R)-tert-butyl 2-amino-2-phenylacetate/HCl (9.877 g, 40.52 mmol) and diisopropylethylamine (14.2 mL, 81.52 mmol) over 6 min, and stirred at similar temperature for 5.5 hours. The volatile component was removed in vacuo, and the residue was partitioned between water (100 mL) and ethyl acetate (200 mL). The organic layer was washed with 1N HCl (25 mL) and saturated NaHCO₃ solution (30 mL), dried (MgSO₄), filtered, and concentrated in vacuo. The resultant colorless oil was triturated from hexanes, filtered and washed with hexanes (100 mL) to provide (R)-tert-butyl 2-(methoxycarbonylamino)-2-phenylacetate as a white solid (7.7 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): 7.98 (d, J=8.0, 1H), 7.37-7.29 (m, 5H), 5.09 (d, J=8, 1H), 3.56 (s, 3H), 1.33 (s, 9H). LC (Cond. I): RT=1.53 min; ˜90% homogeneity index; LC/MS: Anal. Calcd. for [M+Na]⁺ C₁₄H₁₉NNaO₄: 288.12. found 288.15.

TFA (16 mL) was added dropwise to a cooled (ice/water) CH₂Cl₂ (160 mL) solution of the above product over 7 minutes, and the cooling bath was removed and the reaction mixture was stirred for 20 hours. Since the deprotection was still not complete, an additional TFA (1.0 mL) was added and stirring continued for an additional 2 hours. The volatile component was removed in vacuo, and the resulting oil residue was treated with diethyl ether (15 mL) and hexanes (12 mL) to provide a precipitate. The precipitate was filtered and washed with diethyl ether/hexanes (˜1:3 ratio; 30 mL) and dried in vacuo to provide Cap-4 as a fluffy white solid (5.57 g). Optical rotation: −176.9° [c=3.7 mg/mL in H₂O; δ=589 nm]. NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 12.84 (br s, 1H), 7.96 (d, J=8.3, 1H), 7.41-7.29 (m, 5H), 5.14 (d, J=8.3, 1H), 3.55 (s, 3H). LC (Cond. I): RT=1.01 min; >95% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₁₀H₁₂NO₄ 210.08. found 210.17; HRMS: Anal. Calcd. for [M+H]⁺C₁₀H₁₂NO₄ 210.0766. found 210.0756.

A mixture of (R)-2-phenylglycine (1.0 g, 6.62 mmol), 1,4-dibromobutane (1.57 g, 7.27 mmol) and Na₂CO₃ (2.10 g, 19.8 mmol) in ethanol (40 mL) was heated at 100° C. for 21 hours. The reaction mixture was cooled to ambient temperature and filtered, and the filtrate was concentrated in vacuo. The residue was dissolved in ethanol and acidified with 1N HCl to pH 3-4, and the volatile component was removed in vacuo. The resulting crude material was purified by a reverse phase HPLC (water/methanol/TFA) to provide the TFA salt of Cap-5 as a semi-viscous white foam (1.0 g). ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) δ 10.68 (br s, 1H), 7.51 (m, 5H), 5.23 (s, 1H), 3.34 (app br s, 2H), 3.05 (app br s, 2H), 1.95 (app br s, 4H); RT=0.30 minutes (Cond. I); >98% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₁₂H₁₆NO₂: 206.12. found 206.25.

The TFA salt of Cap-6 was synthesized from (R)-2-phenylglycine and 1-bromo-2-(2-bromoethoxy)ethane by using the method of preparation of Cap-5. ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) δ 12.20 (br s, 1H), 7.50 (m, 5H), 4.92 (s, 1H), 3.78 (app br s, 4H), 3.08 (app br s, 2H), 2.81 (app br s, 2H); RT=0.32 minutes (Cond. I); >98%; LC/MS: Anal. Calcd. for [M+H]⁺C₁₂H₁₆NO₃: 222.11. found 222.20; HRMS: Anal. Calcd. for [M+H]⁺C₁₂H₁₆NO₃: 222.1130. found 222.1121.

A CH₂Cl₂ (200 mL) solution of p-toluenesulfonyl chloride (8.65 g, 45.4 mmol) was added dropwise to a cooled (−5° C.) CH₂Cl₂ (200 mL) solution of (S)-benzyl 2-hydroxy-2-phenylacetate (10.0 g, 41.3 mmol), triethylamine (5.75 mL, 41.3 mmol) and 4-dimethylaminopyridine (0.504 g, 4.13 mmol), while maintaining the temperature between −5° C. and 0° C. The reaction was stirred at 0° C. for 9 hours, and then stored in a freezer (−25° C.) for 14 hours. It was allowed to thaw to ambient temperature and washed with water (200 mL), 1N HCl (100 mL) and brine (100 mL), dried (MgSO₄), filtered, and concentrated in vacuo to provide benzyl 2-phenyl-2-(tosyloxy)acetate as a viscous oil which solidified upon standing (16.5 g). The chiral integrity of the product was not checked and that product was used for the next step without further purification. ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) δ 7.78 (d, J=8.6, 2H), 7.43-7.29 (m, 10H), 7.20 (m, 2H), 6.12 (s, 1H), 5.16 (d, J=12.5, 1H), 5.10 (d, J=12.5, 1H), 2.39 (s, 3H). RT=3.00 (Cond. III); >90% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₂₂H₂₀NaO₅S: 419.09. found 419.04.

A THF (75 mL) solution of benzyl 2-phenyl-2-(tosyloxy)acetate (6.0 g, 15.1 mmol), 1-methylpiperazine (3.36 mL, 30.3 mmol) and N,N-diisopropylethylamine (13.2 mL, 75.8 mmol) was heated at 65° C. for 7 hours. The reaction was allowed to cool to ambient temperature and the volatile component was removed in vacuo. The residue was partitioned between ethylacetate and water, and the organic layer was washed with water and brine, dried (MgSO₄), filtered, and concentrated in vacuo. The resulting crude material was purified by flash chromatography (silica gel, ethyl acetate) to provide benzyl 2-(4-methylpiperazin-1-yl)-2-phenylacetate as an orangish-brown viscous oil (4.56 g). Chiral HPLC analysis (Chiralcel OD-H) indicated that the sample is a mixture of enantiomers in a 38.2 to 58.7 ratio. The separation of the enantiomers were effected as follow: the product was dissolved in 120 mL of ethanol/heptane (1:1) and injected (5 mL/injection) on chiral HPLC column (Chiracel OJ, 5 cm ID×50 cm L, 20 μm) eluting with 85:15 Heptane/ethanol at 75 mL/min, and monitored at 220 nm. Enantiomer-1 (1.474 g) and enantiomer-2 (2.2149 g) were retrieved as viscous oil. ¹H NMR (CDCl₃, δ=7.26, 500 MHz) 7.44-7.40 (m, 2H), 7.33-7.24 (m, 6H), 7.21-7.16 (m, 2H), 5.13 (d, J=12.5, 1H), 5.08 (d, J=12.5, 1H), 4.02 (s, 1H), 2.65-2.38 (app br s, 8H), 2.25 (s, 3H). RT=2.10 (Cond. III); >98% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₂₀H₂₅N₂O₂: 325.19. found 325.20.

A methanol (10 mL) solution of either enantiomer of benzyl 2-(4-methylpiperazin-1-yl)-2-phenylacetate (1.0 g, 3.1 mmol) was added to a suspension of 10% Pd/C (120 mg) in methanol (5.0 mL). The reaction mixture was exposed to a balloon of hydrogen, under a careful monitoring, for <50 minutes. Immediately after the completion of the reaction, the catalyst was filtered through diatomaceous earth (Celite®) and the filtrate was concentrated in vacuo to provide Cap-7, contaminated with phenylacetic acid as a tan foam (867.6 mg; mass is above the theoretical yield). The product was used for the next step without further purification. ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) δ 7.44-7.37 (m, 2H), 7.37-7.24 (m, 3H), 3.92 (s, 1H), 2.63-2.48 (app. br s, 2H), 2.48-2.32 (m, 6H), 2.19 (s, 3H); RT=0.31 (Cond. II); >90% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺ C₁₃H₁₉N₂O₂: 235.14; found 235.15; HRMS: Anal. Calcd. for [M+H]⁺ C₁₃H₁₉N₂O₂: 235.1447. found 235.1440.

The synthesis of Cap-8 and Cap-9 was conducted according to the synthesis of Cap-7 by using appropriate amines for the SN₂ displacement step (i.e., 4-hydroxypiperidine for Cap-8 and (S)-3-fluoropyrrolidine for Cap-9) and modified conditions for the separation of the respective stereoisomeric intermediates, as described below.

The enantiomeric separation of the intermediate benzyl 2-(4-hydroxypiperidin-1-yl)-2-phenyl acetate was effected by employing the following conditions: the compound (500 mg) was dissolved in ethanol/heptane (5 mL/45 mL). The resulting solution was injected (5 mL/injection) on a chiral HPLC column (Chiracel OJ, 2 cm ID×25 cm L, 10 μm) eluting with 80:20 heptane/ethanol at 10 mL/min, monitored at 220 nm, to provide 186.3 mg of enantiomer-1 and 209.1 mg of enantiomer-2 as light-yellow viscous oils. These benzyl ester was hydrogenolysed according to the preparation of Cap-7 to provide Cap-8: ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) 7.40 (d, J=7, 2H), 7.28-7.20 (m, 3H), 3.78 (s 1H), 3.46 (m, 1H), 2.93 (m, 1H), 2.62 (m, 1H), 2.20 (m, 2H), 1.70 (m, 2H), 1.42 (m, 2H). RT=0.28 (Cond. II); >98% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₁₃H₁₈NO₃: 236.13. found 236.07; HRMS: Calcd. for [M+H]⁺C₁₃H₁₈NO₃: 236.1287. found 236.1283.

The diastereomeric separation of the intermediate benzyl 2-((S)-3-fluoropyrrolidin-1-yl)-2-phenylacetate was effected by employing the following conditions: the ester (220 mg) was separated on a chiral HPLC column (Chiracel OJ-H, 0.46 cm ID×25 cm L, 5 μm) eluting with 95% CO₂/5% methanol with 0.1% TFA, at 10 bar pressure, 70 mL/min flow rate, and a temperature of 35° C. The HPLC elute for the respective stereoisomers was concentrated, and the residue was dissolved in CH₂Cl₂ (20 mL) and washed with an aqueous medium (10 mL water+1 mL saturated NaHCO₃ solution). The organic phase was dried (MgSO₄), filtered, and concentrated in vacuo to provide 92.5 mg of fraction-1 and 59.6 mg of fraction-2. These benzyl esters were hydrogenolysed according to the preparation of Cap-7 to prepare Caps 9a and 9b. Cap-9a (diastereomer-1; the sample is a TFA salt as a result of purification on a reverse phase HPLC using H₂O/methanol/TFA solvent): ¹H NMR (DMSO-d₆, δ=2.5, 400 MHz) 7.55-7.48 (m, 5H), 5.38 (d of m, J=53.7, 1H), 5.09 (br s, 1H), 3.84-2.82 (br m, 4H), 2.31-2.09 (m, 2H). RT=0.42 (Cond. I); >95% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₁₂H₁₅FNO₂: 224.11. found 224.14; Cap-9b (diastereomer-2): ¹H NMR (DMSO-d₆, δ=2.5, 400 MHz) 7.43-7.21 (m, 5H), 5.19 (d of m, J=55.9, 1H), 3.97 (s, 1H), 2.95-2.43 (m, 4H), 2.19-1.78 (m, 2H). RT=0.44 (Cond. I); LC/MS: Anal. Calcd. for [M+H]⁺ C₁₂H₁₅FNO₂: 224.11. found 224.14.

To a solution of D-proline (2.0 g, 17 mmol) and formaldehyde (2.0 mL of 37% wt. in H₂O) in methanol (15 mL) was added a suspension of 10% Pd/C (500 mg) in methanol (5 mL). The mixture was stirred under a balloon of hydrogen for 23 hours. The reaction mixture was filtered through diatomaceous earth (Celite®) and concentrated in vacuo to provide Cap-10 as an off-white solid (2.15 g). ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) 3.42 (m, 1H), 3.37 (dd, J=9.4, 6.1, 1H), 2.85-2.78 (m, 1H), 2.66 (s, 3H), 2.21-2.13 (m, 1H), 1.93-1.84 (m, 2H), 1.75-1.66 (m, 1H). RT=0.28 (Cond. II); >98% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺ C₆H₁₂NO₂: 130.09. found 129.96.

A mixture of (2S,4R)-4-fluoropyrrolidine-2-carboxylic acid (0.50 g, 3.8 mmol), formaldehyde (0.5 mL of 37% wt. in H₂O), 12 N HCl (0.25 mL) and 10% Pd/C (50 mg) in methanol (20 mL) was stirred under a balloon of hydrogen for 19 hours. The reaction mixture was filtered through diatomaceous earth (Celite®) and the filtrate was concentrated in vacuo. The residue was recrystallized from isopropanol to provide the HCl salt of Cap-11 as a white solid (337.7 mg). ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) 5.39 (d m, J=53.7, 1H), 4.30 (m, 1H), 3.90 (ddd, J=31.5, 13.5, 4.5, 1H), 3.33 (dd, J=25.6, 13.4, 1H), 2.85 (s, 3H), 2.60-2.51 (m, 1H), 2.39-2.26 (m, 1H). RT=0.28 (Cond. II); >98% homogeneity index; LC/MS: Anal. Calcd. for [M+H]⁺C₆H₁₁FNO₂: 148.08. found 148.06.

L-Alanine (2.0 g, 22.5 mmol) was dissolved in 10% aqueous sodium carbonate solution (50 mL), and a THF (50 mL) solution of methyl chloroformate (4.0 mL) was added to it. The reaction mixture was stirred under ambient conditions for 4.5 hours and concentrated in vacuo. The resulting white solid was dissolved in water and acidified with 1N HCl to a pH ˜2-3. The resulting solutions was extracted with ethyl acetate (3×100 mL), and the combined organic phase was dried (Na₂SO₄), filtered, and concentrated in vacuo to provide a colorless oil (2.58 g). 500 mg of this material was purified by a reverse phase HPLC (H₂O/methanol/TFA) to provide 150 mg of Cap-12 as a colorless oil. ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) 7.44 (d, J=7.3, 0.8H), 7.10 (br s, 0.2H), 3.97 (m, 1H), 3.53 (s, 3H), 1.25 (d, J=7.3, 3H).

A mixture of L-alanine (2.5 g, 28 mmol), formaldehyde (8.4 g, 37 wt. %), 1N HCl (30 mL) and 10% Pd/C (500 mg) in methanol (30 mL) was stirred under a hydrogen atmosphere (50 psi) for 5 hours. The reaction mixture was filtered through diatomaceous earth (Celite®) and the filtrate was concentrated in vacuo to provide the HCl salt of Cap-13 as an oil which solidified upon standing under vacuum (4.4 g; the mass is above theoretical yield). The product was used without further purification. ¹H NMR (DMSO-d₆, δ=2.5, 500 MHz) δ 12.1 (br s, 1H), 4.06 (q, J=7.4, 1H), 2.76 (s, 6H), 1.46 (d, J=7.3, 3H).

Step 1: A mixture of (R)-(−)-D-phenylglycine tert-butyl ester (3.00 g, 12.3 mmol), NaBH₃CN (0.773 g, 12.3 mmol), KOH (0.690 g, 12.3 mmol) and acetic acid (0.352 mL, 6.15 mmol) were stirred in methanol at 0° C. To this mixture was added glutaric dialdehyde (2.23 mL, 12.3 mmol) dropwise over 5 minutes. The reaction mixture was stirred as it was allowed to warm to ambient temperature and stirring was continued at the same temperature for 16 hours. The solvent was subsequently removed and the residue was partitioned with 10% aqueous NaOH and ethyl acetate. The organic phase was separated, dried (MgSO₄), filtered and concentrated to dryness to provide a clear oil. This material was purified by reverse-phase preparative HPLC (Primesphere C-18, 30×100 mm; CH₃CN—H₂O-0.1% TFA) to give the intermediate ester (2.70 g, 56%) as a clear oil. ¹H NMR (400 MHz, CDCl₃) δ 7.53-7.44 (m, 3H), 7.40-7.37 (m, 2H), 3.87 (d, J=10.9 Hz, 1H), 3.59 (d, J=10.9 Hz, 1H), 2.99 (t, J=11.2 Hz, 1H), 2.59 (t, J=11.4 Hz, 1H), 2.07-2.02 (m, 2H), 1.82 (d, J=1.82 Hz, 3H), 1.40 (s, 9H). LC/MS: Anal. Calcd. for C₁₇H₂₅NO₂: 275. found: 276 (M+H)⁺.

Step 2: To a stirred solution of the intermediate ester (1.12 g, 2.88 mmol) in dichloromethane (10 mL) was added TFA (3 mL). The reaction mixture was stirred at ambient temperature for 4 hours and then it was concentrated to dryness to give a light yellow oil. The oil was purified using reverse-phase preparative HPLC (Primesphere C-18, 30×100 mm; CH₃CN—H₂O-0.1% TFA). The appropriate fractions were combined and concentrated to dryness in vacuo. The residue was then dissolved in a minimum amount of methanol and applied to applied to MCX LP extraction cartridges (2×6 g). The cartridges were rinsed with methanol (40 mL) and then the desired compound was eluted using 2M ammonia in methanol (50 mL). Product-containing fractions were combined and concentrated and the residue was taken up in water. Lyophilization of this solution provided the title compound (0.492 g, 78%) as a light yellow solid. ¹H NMR (DMSO-d₆) δ 7.50 (s, 5H), 5.13 (s, 1H), 3.09 (br s, 2H), 2.92-2.89 (m, 2H), 1.74 (m, 4H), 1.48 (br s, 2H). LC/MS: Anal. Calcd. for C₁₃H₁₇NO₂: 219. found: 220 (M+H)⁺.

Step 1: (S)-1-Phenylethyl 2-bromo-2-phenylacetate: To a mixture of α-bromophenylacetic acid (10.75 g, 0.050 mol), (S)-(−)-1-phenylethanol (7.94 g, 0.065 mol) and DMAP (0.61 g, 5.0 mmol) in dry dichloromethane (100 mL) was added solid EDCI (12.46 g, 0.065 mol) all at once. The resulting solution was stirred at room temperature under Ar for 18 hours and then it was diluted with ethyl acetate, washed (H₂O ×2, brine), dried (Na₂SO₄), filtered, and concentrated to give a pale yellow oil. Flash chromatography (SiO₂/hexane-ethyl acetate, 4:1) of this oil provided the title compound (11.64 g, 73%) as a white solid. ¹H NMR (400 MHz, CDCl₃) δ 7.53-7.17 (m, 10H), 5.95 (q, J=6.6 Hz, 0.5H), 5.94 (q, J=6.6 Hz, 0.5H), 5.41 (s, 0.5H), 5.39 (s, 0.5H), 1.58 (d, J=6.6 Hz, 1.5H), 1.51 (d, J=6.6 Hz, 1.5H).

Step 2: (S)-1-Phenylethyl (R)-2-(4-hydroxy-4-methylpiperidin-1-yl)-2-phenylacetate: To a solution of (S)-1-phenylethyl 2-bromo-2-phenylacetate (0.464 g, 1.45 mmol) in THF (8 mL) was added triethylamine (0.61 mL, 4.35 mmol), followed by tetrabutylammonium iodide (0.215 g, 0.58 mmol). The reaction mixture was stirred at room temperature for 5 minutes and then a solution of 4-methyl-4-hydroxypiperidine (0.251 g, 2.18 mmol) in THF (2 mL) was added. The mixture was stirred for 1 hour at room temperature and then it was heated at 55-60° C. (oil bath temperature) for 4 hours. The cooled reaction mixture was then diluted with ethyl acetate (30 mL), washed (H₂O ×2, brine), dried (MgSO₄), filtered and concentrated. The residue was purified by silica gel chromatography (0-60% ethyl acetate-hexane) to provide first the (S,R)-isomer of the title compound (0.306 g, 60%) as a white solid and then the corresponding (S,S)-isomer (0.120 g, 23%), also as a white solid. (S,R)-isomer; ¹H NMR (CD₃OD) δ 7.51-7.45 (m, 2H), 7.41-7.25 (m, 8H), 5.85 (q, J=6.6 Hz, 1H), 4.05 (s, 1H), 2.56-2.45 (m, 2H), 2.41-2.29 (m, 2H), 1.71-1.49 (m, 4H), 1.38 (d, J=6.6 Hz, 3H), 1.18 (s, 3H). LCMS: Anal. Calcd. for C₂₂H₂₇NO₃: 353. found: 354 (M+H)⁺. (S,S)-isomer: ¹H NMR (CD₃OD) δ 7.41-7.30 (m, 5H), 7.20-7.14 (m, 3H), 7.06-7.00 (m, 2H), 5.85 (q, J=6.6 Hz, 1H), 4.06 (s, 1H), 2.70-2.60 (m, 1H), 2.51 (dt, J=6.6, 3.3 Hz, 1H), 2.44-2.31 (m, 2H), 1.75-1.65 (m, 1H), 1.65-1.54 (m, 3H), 1.50 (d, J=6.8 Hz, 3H), 1.20 (s, 3H). LCMS: Anal. Calcd. for C₂₂H₂₇NO₃: 353. found: 354 (M+H)⁺.

Step 3: (R)-2-(4-Hydroxy-4-methylpiperidin-1-yl)-2-phenylacetic acid: To a solution of (S)-1-phenylethyl (R)-2-(4-hydroxy-4-methylpiperidin-1-yl)-2-phenylacetate (0.185 g, 0.52 mmol) in dichloromethane (3 mL) was added trifluoroacetic acid (1 mL) and the mixture was stirred at room temperature for 2 hours. The volatiles were subsequently removed in vacuo and the residue was purified by reverse-phase preparative HPLC (Primesphere C-18, 20×100 mm; CH₃CN—H₂O-0.1% TFA) to give the title compound (as TFA salt) as a pale bluish solid (0.128 g, 98%). LCMS: Anal. Calcd. for C₁₄H₁₉NO₃: 249. found: 250 (M+H)⁺.

Step 1: (S)-1-Phenylethyl 2-(2-fluorophenyl)acetate: A mixture of 2-fluorophenylacetic acid (5.45 g, 35.4 mmol), (S)-1-phenylethanol (5.62 g, 46.0 mmol), EDCI (8.82 g, 46.0 mmol) and DMAP (0.561 g, 4.60 mmol) in CH₂Cl₂ (100 mL) was stirred at room temperature for 12 hours. The solvent was then concentrated and the residue partitioned with H₂O-ethyl acetate. The phases were separated and the aqueous layer back-extracted with ethyl acetate (2×). The combined organic phases were washed (H₂O, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography (Biotage/0-20% ethyl acetate-hexane) to provide the title compound as a colorless oil (8.38 g, 92%). ¹H NMR (400 MHz, CD₃OD) δ 7.32-7.23 (m, 7H), 7.10-7.04 (m, 2), 5.85 (q, J=6.5 Hz, 1H), 3.71 (s, 2H), 1.48 (d, J=6.5 Hz, 3H).

Step 2: (R)-((S)-1-Phenylethyl) 2-(2-fluorophenyl)-2-(piperidin-1-yl)acetate: To a solution of (S)-1-phenylethyl 2-(2-fluorophenyl)acetate (5.00 g, 19.4 mmol) in THF (1200 mL) at 0° C. was added DBU (6.19 g, 40.7 mmol) and the solution was allowed to warm to room temperature while stirring for 30 minutes. The solution was then cooled to −78° C. and a solution of CBr₄ (13.5 g, 40.7 mmol) in THF (100 mL) was added and the mixture was allowed to warm to −10° C. and stirred at this temperature for 2 hours. The reaction mixture was quenched with saturated aq. NH₄Cl and the layers were separated. The aqueous layer was back-extracted with ethyl acetate (2×) and the combined organic phases were washed (H₂O, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo. To the residue was added piperidine (5.73 mL, 58.1 mmol) and the solution was stirred at room temperature for 24 hours. The volatiles were then concentrated in vacuo and the residue was purified by silica gel chromatography (Biotage/0-30% diethyl ether-hexane) to provide a pure mixture of diastereomers (2:1 ratio by ¹H NMR) as a yellow oil (2.07 g, 31%), along with unreacted starting material (2.53 g, 51%). Further chromatography of the diastereomeric mixture (Biotage/0-10% diethyl ether-toluene) provided the title compound as a colorless oil (0.737 g, 11%). ¹H NMR (400 MHz, CD₃OD) δ 7.52 (ddd, J=9.4, 7.6, 1.8 Hz, 1H), 7.33-7.40 (m, 1), 7.23-7.23 (m, 4H), 7.02-7.23 (m, 4H), 5.86 (q, J=6.6 Hz, 1H), 4.45 (s, 1H), 2.39-2.45 (m, 4H), 1.52-1.58 (m, 4H), 1.40-1.42 (m, 1H), 1.38 (d, J=6.6 Hz, 3H). LCMS: Anal. Calcd. for C₂₁H₂₄FNO₂: 341. found: 342 (M+H)⁺.

Step 3: (R)-2-(2-fluorophenyl)-2-(piperidin-1-yl)acetic acid: A mixture of (R)-((S)-1-phenylethyl) 2-(2-fluorophenyl)-2-(piperidin-1-yl)acetate (0.737 g, 2.16 mmol) and 20% Pd(OH)₂/C (0.070 g) in ethanol (30 mL) was hydrogenated at room temperature and atmospheric pressure (H₂ balloon) for 2 hours. The solution was then purged with Ar, filtered through diatomaceous earth (Celite®), and concentrated in vacuo. This provided the title compound as a colorless solid (0.503 g, 98%). ¹H NMR (400 MHz, CD₃OD) δ 7.65 (ddd, J=9.1, 7.6, 1.5 Hz, 1H), 7.47-7.53 (m, 1H), 7.21-7.30 (m, 2H), 3.07-3.13 (m, 4H), 1.84 (br s, 4H), 1.62 (br s, 2H). LCMS: Anal. Calcd. for C₁₃H₁₆FNO₂: 237. found: 238 (M+H)⁺.

Step 1: (S)-1-Phenylethyl (R)-2-(4-hydroxy-4-phenylpiperidin-1-yl)-2-phenylacetate: To a solution of (S)-1-phenylethyl 2-bromo-2-phenylacetate (1.50 g, 4.70 mmol) in THF (25 mL) was added triethylamine (1.31 mL, 9.42 mmol), followed by tetrabutylammonium iodide (0.347 g, 0.94 mmol). The reaction mixture was stirred at room temperature for 5 minutes and then a solution of 4-phenyl-4-hydroxypiperidine (1.00 g, 5.64 mmol) in THF (5 mL) was added. The mixture was stirred for 16 hours and then it was diluted with ethyl acetate (100 mL), washed (H₂O ×2, brine), dried (MgSO₄), filtered and concentrated. The residue was purified on a silica gel column (0-60% ethyl acetate-hexane) to provide an approximately 2:1 mixture of diastereomers, as judged by ¹H NMR. Separation of these isomers was performed using supercritical fluid chromatography (Chiralcel OJ-H, 30×250 mm; 20% ethanol in CO₂ at 35° C.), to give first the (R)-isomer of the title compound (0.534 g, 27%) as a yellow oil and then the corresponding (S)-isomer (0.271 g, 14%), also as a yellow oil. (S,R)-isomer: ¹H NMR (400 MHz, CD₃OD) δ 7.55-7.47 (m, 4H), 7.44-7.25 (m, 10H), 7.25-7.17 (m, 1H), 5.88 (q, J=6.6 Hz, 1H), 4.12 (s, 1H), 2.82-2.72 (m, 1H), 2.64 (dt, J=11.1, 2.5 Hz, 1H), 2.58-2.52 (m, 1H), 2.40 (dt, J=11.1, 2.5 Hz, 1H), 2.20 (dt, J=12.1, 4.6 Hz, 1H), 2.10 (dt, J=12.1, 4.6 Hz, 1H), 1.72-1.57 (m, 2H), 1.53 (d, J=6.5 Hz, 3H). LCMS: Anal. Calcd. for C₂₇H₂₉NO₃: 415. found: 416 (M+H)⁺; (S,S)-isomer: H′NMR (400 MHz, CD₃OD) δ 7.55-7.48 (m, 2H), 7.45-7.39 (m, 2H), 7.38-7.30 (m, 5H), 7.25-7.13 (m, 4H), 7.08-7.00 (m, 2H), 5.88 (q, J=6.6 Hz, 1H), 4.12 (s, 1H), 2.95-2.85 (m, 1H), 2.68 (dt, J=11.1, 2.5 Hz, 1H), 2.57-2.52 (m, 1H), 2.42 (dt, J=11.1, 2.5 Hz, 1H), 2.25 (dt, J=12.1, 4.6 Hz, 1H), 2.12 (dt, J=12.1, 4.6 Hz, 1H), 1.73 (dd, J=13.6, 3.0 Hz, 1H), 1.64 (dd, J=13.6, 3.0 Hz, 1H), 1.40 (d, J=6.6 Hz, 3H). LCMS: Anal. Calcd. for C₂₇H₂₉NO₃: 415. found: 416 (M+H)⁺.

The following esters were prepared in similar fashion:

Intermediate-17a

Diastereomer 1: ¹H NMR (500 MHz, DMSO-d₆) δ ppm 1.36 (d, J = 6.41 Hz, 3H) 2.23-2.51 (m, 4H) 3.35 (s, 4H) 4.25 (s, 1H) 5.05 (s, 2H) 5.82 (d, J = 6.71 Hz, 1H) 7.15-7.52 (m, 15H). LCMS: Anal. Calcd. for: C₂₈H₃₀N₂O₄ 458.22; Found: 459.44 (M + H)⁺. Diastereomer 2: ¹H NMR (500 MHz, DMSO-d₆) δ ppm 1.45 (d, J = 6.71 Hz, 3H) 2.27-2.44 (m, 4H) 3.39 (s, 4H) 4.23 (s, 1H) 5.06 (s, 2H) 5.83 (d, J = 6.71 Hz, 1H) 7.12 (dd, J = 6.41, 3.05 Hz, 2H) 7.19-7.27 (m, 3H) 7.27- 7.44 (m, 10H). LCMS: Anal. Calcd. for: C₂₈H₃₀N₂O₄ 458.22; Found: 459.44 (M + H)⁺. Intermediate-17b

Diasteromer 1: RT = 11.76 minutes (Cond'n II); LCMS: Anal. Calcd. for: C₂₀H₂₂N₂O₃ 338.16 Found: 339.39 (M + H)⁺; Diastereomer 2: RT = 10.05 minutes (Cond'n II); LCMS: Anal. Calcd. for: C₂₀H₂₂N₂O₃ 338.16; Found: 339.39 (M + H)⁺. Intermediate-17c

Diastereomer 1: T_(R) = 4.55 minutes (Cond'n I); LCMS: Anal. Calcd. for: C₂₁H₂₆N₂O₂ 338.20 Found: 339.45 (M + H)⁺; Diastereomer 2: T_(R) = 6.00 minutes (Cond'n I); LCMS: Anal. Calcd. for: C₂₁H₂₆N₂O₂ 338.20 Found: 339.45 (M + H)⁺. Intermediate-17d

Diastereomer 1: RT = 7.19 minutes (Cond'n I); LCMS: Anal. Calcd. for: C₂₇H₂₉NO₂ 399.22 Found: 400.48 (M + H)⁺; Diastereomer 2: RT = 9.76 minutes (Cond'n I); LCMS: Anal. Calcd. for: C₂₇H₂₉NO₂ 399.22 Found: 400.48 (M + H)⁺.

Chiral SFC Conditions for Determining Retention Time Condition I Column: Chiralpak AD-H Column, 4.62×50 mm, 5 μm

Solvents: 90% CO2-10% methanol with 0.1% DEA

Temp: 35° C. Pressure: 150 bar

Flow rate: 2.0 mL/min. UV monitored @ 220 nm Injection: 1.0 mg/3 mL methanol

Condition II Column: Chiralcel OD-H Column, 4.62×50 mm, 5 μm

Solvents: 90% CO2-10% methanol with 0.1% DEA

Temp: 35° C. Pressure: 150 bar

Flow rate: 2.0 mL/min. UV monitored @ 220 nm Injection: 1.0 mg/mL methanol

Cap 17, Step 2; (R)-2-(4-Hydroxy-4-phenylpiperidin-1-yl)-2-phenylacetic acid: To a solution of (S)-1-phenylethyl (R)-2-(4-hydroxy-4-phenylpiperidin-1-yl)-2-phenylacetate (0.350 g, 0.84 mmol) in dichloromethane (5 mL) was added trifluoroacetic acid (1 mL) and the mixture was stirred at room temperature for 2 hours. The volatiles were subsequently removed in vacuo and the residue was purified by reverse-phase preparative HPLC (Primesphere C-18, 20×100 mm; CH₃CN—H₂O-0.1% TFA) to give the title compound (as TFA salt) as a white solid (0.230 g, 88%). LCMS: Anal. Calcd. for C₁₉H₂₁NO₃: 311.15. found: 312 (M+H)⁺.

The following carboxylic acids were prepared in optically pure form in a similar fashion:

Cap-17a

RT = 2.21 (Cond'n II); ¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.20-2.35 (m, 2H) 2.34-2.47 (m, 2H) 3.37 (s, 4H) 3.71 (s, 1H) 5.06 (s, 2H) 7.06-7.53 (m, 10H). LCMS: Anal. Calcd. for: C₂₀H₂₂N₂O₄ 354.16; Found: 355.38 (M + H)⁺. Cap-17b

RT = 0.27 (Cond'n III); LCMS: Anal. Calcd. for: C₁₂H₁₄N₂O₃ 234.10; Found: 235.22 (M + H)⁺. Cap-17c

RT = 0.48 (Cond'n II); LCMS: Anal. Calcd. for: C₁₃H₁₈N₂O₂ 234.14; Found: 235.31 (M + H)⁺. Cap-17d

RT.2.21 (Cond'n I); LCMS: Anal. Calcd. for: C₁₉H₂₁NO₂ 295.16; Found: 296.33 (M + H)⁺.

LCMS Conditions for Determining Retention Time Condition I Column: Phenomenex-Luna 4.6×50 mm S10 Start % B=0 Final % B=100 Gradient Time=4 min

Flow Rate=4 mL/min

Wavelength=220

Solvent A=10% methanol—90% H₂O—0.1% TFA Solvent B=90% methanol—10% H₂O—0.1% TFA

Condition II Column: Waters-Sunfire 4.6×50 mm S5 Start % B=0 Final % B=100 Gradient Time=2 min

Flow Rate=4 mL/min

Wavelength=220

Solvent A=10% methanol—90% H₂O—0.1% TFA Solvent B=90% methanol—10% H₂O—0.1% TFA

Condition III Column: Phenomenex 10μ 3.0×50 mm Start % B=0 Final % B=100 Gradient Time=2 min

Flow Rate=4 mL/min

Wavelength=220

Solvent A=10% methanol—90% H₂O—0.1% TFA Solvent B=90% methanol—10% H₂O—0.1% TFA

Step 1; (R,S)-Ethyl 2-(4-pyridyl)-2-bromoacetate: To a solution of ethyl 4-pyridylacetate (1.00 g, 6.05 mmol) in dry THF (150 mL) at 0° C. under argon was added DBU (0.99 mL, 6.66 mmol). The reaction mixture was allowed to warm to room temperature over 30 minutes and then it was cooled to −78° C. To this mixture was added CBr₄ (2.21 g, 6.66 mmol) and stirring was continued at −78° C. for 2 hours. The reaction mixture was then quenched with sat. aq. NH₄Cl and the phases were separated. The organic phase was washed (brine), dried (Na₂SO₄), filtered, and concentrated in vacuo. The resulting yellow oil was immediately purified by flash chromatography (SiO₂/hexane-ethyl acetate, 1:1) to provide the title compound (1.40 g, 95%) as a somewhat unstable yellow oil. ¹H NMR (400 MHz, CDCl₃) δ 8.62 (dd, J=4.6, 1.8 Hz, 2H), 7.45 (dd, J=4.6, 1.8 Hz, 2H), 5.24 (s, 1H), 4.21-4.29 (m, 2H), 1.28 (t, J=7.1 Hz, 3H). LCMS: Anal. Calcd. for C₉H₁₀BrNO₂: 242, 244. found: 243, 245 (M+H)⁺.

Step 2; (R,S)-Ethyl 2-(4-pyridyl)-2-(N,N-dimethylamino)acetate: To a solution of (R,S)-ethyl 2-(4-pyridyl)-2-bromoacetate (1.40 g, 8.48 mmol) in DMF (10 mL) at room temperature was added dimethylamine (2M in THF, 8.5 mL, 17.0 mmol). After completion of the reaction (as judged by thin layer chromatography) the volatiles were removed in vacuo and the residue was purified by flash chromatography (Biotage, 40+M SiO₂ column; 50%-100% ethyl acetate-hexane) to provide the title compound (0.539 g, 31%) as a light yellow oil. ¹H NMR (400 MHz, CDCl₃) δ 8.58 (d, J=6.0 Hz, 2H), 7.36 (d, J=6.0 Hz, 2H), 4.17 (m, 2H), 3.92 (s, 1H), 2.27 (s, 6H), 1.22 (t, J=7.0 Hz). LCMS: Anal. Calcd. for C₁₁H₁₆N₂O₂: 208. found: 209 (M+H)⁺.

Step 3; (R,S)-2-(4-Pyridyl)-2-(N,N-dimethylamino)acetic acid: To a solution of (R,S)-ethyl 2-(4-pyridyl)-2-(N,N-dimethylamino)acetate (0.200 g, 0.960 mmol) in a mixture of THF-methanol-H₂O (1:1:1, 6 mL) was added powdered LiOH (0.120 g, 4.99 mmol) at room temperature. The solution was stirred for 3 hours and then it was acidified to pH 6 using 1N HCl. The aqueous phase was washed with ethyl acetate and then it was lyophilized to give the dihydrochloride of the title compound as a yellow solid (containing LiCl). The product was used as such in subsequent steps. ¹H NMR (400 MHz, DMSO-d₆) δ 8.49 (d, J=5.7 Hz, 2H), 7.34 (d, J=5.7 Hz, 2H), 3.56 (s, 1H), 2.21 (s, 6H).

The following examples were prepared in similar fashion using the method described above;

Cap-19

LCMS: Anal. Calcd. for C₉H₁₂N₂O₂: 180; found: 181 (M + H)⁺. Cap-20

LCMS: no ionization. ¹H NMR (400 MHz, CD₃OD) δ 8.55 (d, J = 4.3 Hz, 1H), 7.84 (app t, J = 5.3 Hz, 1H), 7.61 (d, J = 7.8 Hz, 1H), 7.37 (app t, J = 5.3 Hz, 1H), 4.35 (s,1H), 2.60 (s, 6H). Cap-21

LCMS: Anal. Calcd. for C₉H₁₁ClN₂O₂: 214, 216; found: 215, 217 (M + H)⁺. Cap-22

LCMS: Anal. Calcd. for C₁₀H₁₂N₂O₄: 224; found: 225 (M + H)⁺. Cap-23

LCMS: Anal. Calcd. for C₁₄H₁₅NO₂: 229; found: 230 (M + H)⁺. Cap-24

LCMS: Anal. Calcd. for C₁₁H₁₂F₃NO₂: 247; found: 248 (M + H)⁺. Cap-25

LCMS: Anal. Calcd. for C₁₁H₁₂F₃NO₂: 247; found: 248 (M + H)⁺. Cap-26

LCMS: Anal. Calcd. for C₁₀H₁₂FNO₂: 197; found: 198 (M + H)⁺. Cap-27

LCMS: Anal. Calcd. for C₁₀H₁₂FNO₂: 247; found: 248 (M + H)⁺. Cap-28

LCMS: Anal. Calcd. for C₁₀H₁₂ClNO₂: 213; found: 214 (M + H)⁺. Cap-29

LCMS: Anal. Calcd. for C₁₀H₁₂ClNO₂: 213; found: 214 (M + H)⁺. Cap-30

LCMS: Anal. Calcd. for C₁₀H₁₂ClNO₂: 213; found: 214 (M + H)⁺. Cap-31

LCMS: Anal. Calcd. for C₈H₁₂N₂O₂S: 200; found: 201 (M + H)⁺. Cap-32

LCMS: Anal. Calcd. for C₈H₁₁NO₂S: 185; found: 186 (M + H)⁺. Cap-33

LCMS: Anal. Calcd. for C₈H₁₁NO₂S: 185; found: 186 (M + H)⁺. Cap-34

LCMS: Anal. Calcd. for C₁₁H₁₂N₂O₃: 220; found: 221 (M + H)⁺. Cap-35

LCMS: Anal. Calcd. for C₁₂H₁₃NO₂S: 235; found: 236 (M + H)⁺. Cap-36

LCMS: Anal. Calcd. for C₁₂H₁₄N₂O₂S: 250; found: 251 (M + H)⁺.

Step 1; (R,S)-Ethyl 2-(quinolin-3-yl)-2-(N,N-dimethylamino)-acetate: A mixture of ethyl N,N-dimethylaminoacetate (0.462 g, 3.54 mmol), K₃PO₄ (1.90 g, 8.95 mmol), Pd(t-Bu₃P)₂ (0.090 g, 0.176 mmol) and toluene (10 mL) was degassed with a stream of Ar bubbles for 15 minutes. The reaction mixture was then heated at 100° C. for 12 hours, after which it was cooled to room temperature and poured into H₂O. The mixture was extracted with ethyl acetate (2×) and the combined organic phases were washed (H₂O, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo. The residue was purified first by reverse-phase preparative HPLC (Primesphere C-18, 30×100 min; CH₃CN—H₂O-5 mM NH₄OAc) and then by flash chromatography (SiO₂/hexane-ethyl acetate, 1:1) to provide the title compound (0.128 g, 17%) as an orange oil. ¹H NMR (400 MHz, CDCl₃) δ 8.90 (d, J=2.0 Hz, 1H), 8.32 (d, J=2.0 Hz, 1H), 8.03-8.01 (m, 2H), 7.77 (ddd, J=8.3, 6.8, 1.5 Hz, 1H), 7.62 (ddd, J=8.3, 6.8, 1.5 Hz, 1H), 4.35 (s, 1H), 4.13 (m, 2H), 2.22 (s, 6H), 1.15 (t, J=7.0 Hz, 3H). LCMS: Anal. Calcd. for C₁₅H₁₈N₂O₂: 258. found: 259 (M+H)⁺.

Step 2; (R,S) 2-(Quinolin-3-yl)-2-(N,N-dimethylamino)acetic acid: A mixture of (R,S)-ethyl 2-(quinolin-3-yl)-2-(N,N-dimethylamino)acetate (0.122 g, 0.472 mmol) and 6M HCl (3 mL) was heated at 100° C. for 12 hours. The solvent was removed in vacuo to provide the dihydrochloride of the title compound (0.169 g, >100%) as a light yellow foam. The unpurified material was used in subsequent steps without further purification. LCMS: Anal. Calcd. for C₁₃H₁₄N₂O₂: 230. found: 231 (M+H)⁺.

Step 1; (R)-((S)-1-phenylethyl) 2-(dimethylamino)-2-(2-fluorophenyl)acetate and (S)-((S)-1-phenylethyl) 2-(dimethylamino)-2-(2-fluorophenyl)acetate: To a mixture of (RS)-2-(dimethylamino)-2-(2-fluorophenyl)acetic acid (2.60 g, 13.19 mmol), DMAP (0.209 g, 1.71 mmol) and (S)-1-phenylethanol (2.09 g, 17.15 mmol) in CH₂Cl₂ (40 mL) was added EDCI (3.29 g, 17.15 mmol) and the mixture was allowed to stir at room temperature for 12 hours. The solvent was then removed in vacuo and the residue partitioned with ethyl acetate-H₂O. The layers were separated, the aqueous layer was back-extracted with ethyl acetate (2×) and the combined organic phases were washed (H₂O, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography (Biotage/0-50% diethyl ether-hexane). The resulting pure diastereomeric mixture was then separated by reverse-phase preparative HPLC (Primesphere C-18, 30×100 mm; CH₃CN—H₂O-0.1% TFA) to give first (S)-1-phenethyl (R)-2-(dimethylamino)-2-(2-fluorophenyl)acetate (0.501 g, 13%) and then (S)-1-phenethyl (S)-2-(dimethylamino)-2-(2-fluorophenyl)-acetate (0.727 g. 18%), both as their TFA salts. (S,R)-isomer: ¹H NMR (400 MHz, CD₃OD) δ 7.65-7.70 (m, 1H), 7.55-7.60 (ddd, J=9.4, 8.1, 1.5 Hz, 1H), 7.36-7.41 (m, 2H), 7.28-7.34 (m, 5H), 6.04 (q, J=6.5 Hz, 1H), 5.60 (s, 1H), 2.84 (s, 6H), 1.43 (d, J=6.5 Hz, 3H). LCMS: Anal. Calcd. for C₁₈H₂₀FNO₂: 301. found: 302 (M+H)⁺; (S,S)-isomer: ¹H NMR (400 MHz, CD₃OD) δ 7.58-7.63 (m, 1H), 7.18-7.31 (m, 6H), 7.00 (dd, J=8.5, 1.5 Hz, 2H), 6.02 (q, J=6.5 Hz, 1H), 5.60 (s, 1H), 2.88 (s, 6H), 1.54 (d, J=6.5 Hz, 3H). LCMS: Anal. Calcd. for C₁₈H₂₀FNO₂: 301. found: 302 (M+H)⁺.

Step 2; (R)-2-(dimethylamino)-2-(2-fluorophenyl)acetic acid: A mixture of (R)-((S)-1-phenylethyl) 2-(dimethylamino)-2-(2-fluorophenyl)acetate TFA salt (1.25 g, 3.01 mmol) and 20% Pd(OH)₂/C (0.125 g) in ethanol (30 mL) was hydrogenated at room temperature and atmospheric pressure (H₂ balloon) for 4 hours. The solution was then purged with Ar, filtered through diatomaceous earth (Celite®), and concentrated in vacuo. This gave the title compound as a colorless solid (0.503 g, 98%). ¹H NMR (400 MHz, CD₃OD) δ 7.53-7.63 (m, 2H), 7.33-7.38 (m, 2H), 5.36 (s, 1H), 2.86 (s, 6H). LCMS: Anal. Calcd. for C₁₀H₁₂FNO₂: 197. found: 198 (M+H)⁺.

The S-isomer could be obtained from (S)-((S)-1-phenylethyl) 2-(dimethylamino)-2-(2-fluorophenyl)acetate TFA salt in similar fashion.

A mixture of (R)-(2-chlorophenyl)glycine (0.300 g, 1.62 mmol), formaldehyde (35% aqueous solution, 0.80 mL, 3.23 mmol) and 20% Pd(OH)₂/C (0.050 g) was hydrogenated at room temperature and atmospheric pressure (H₂ balloon) for 4 hours. The solution was then purged with Ar, filtered through diatomaceous earth (Celite®) and concentrated in vacuo. The residue was purified by reverse-phase preparative HPLC (Primesphere C-18, 30×100 mm; CH₃CN—H₂O-0.1% TFA) to give the TFA salt of the title compound (R)-2-(dimethylamino)-2-(2-chlorophenyl)acetic acid as a colorless oil (0.290 g, 55%). ¹H NMR (400 MHz, CD₃OD) δ 7.59-7.65 (m, 2H), 7.45-7.53 (m, 2H), 5.40 (s, 1H), 2.87 (s, 6H). LCMS: Anal. Calcd. for C₁₀H₁₂ClNO₂: 213. found: 214 (M+H)⁺.

To an ice-cold solution of (R)-(2-chlorophenyl)glycine (1.00 g, 5.38 mmol) and NaOH (0.862 g, 21.6 mmol) in H₂O (5.5 mL) was added methyl chloroformate (1.00 mL, 13.5 mmol) dropwise. The mixture was allowed to stir at 0° C. for 1 hour and then it was acidified by the addition of conc. HCl (2.5 mL). The mixture was extracted with ethyl acetate (2×) and the combined organic phase was washed (H₂O, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo to give the title compound (R)-2-(methoxycarbonylamino)-2-(2-chlorophenyl)acetic acid as a yellow-orange foam (1.31 g, 96%). ¹H NMR (400 MHz, CD₃OD) δ 7.39-7.43 (m, 2H), 7.29-7.31 (m, 2H), 5.69 (s, 1H), 3.65 (s, 3H). LCMS: Anal. Calcd. for C₁₀H₁₀ClNO₄: 243. found: 244 (M+H)⁺.

To a suspension of 2-(2-(chloromethyl)phenyl)acetic acid (2.00 g, 10.8 mmol) in THF (20 mL) was added morpholine (1.89 g, 21.7 mmol) and the solution was stirred at room temperature for 3 hours. The reaction mixture was then diluted with ethyl acetate and extracted with H₂O (2×). The aqueous phase was lyophilized and the residue was purified by silica gel chromatography (Biotage/0-10% methanol-CH₂Cl₂) to give the title compound 2-(2-(Morpholinomethyl)phenyl)acetic acid as a colorless solid (2.22 g, 87%). ¹H NMR (400 MHz, CD₃OD) δ 7.37-7.44 (m, 3H), 7.29-7.33 (m, 1H), 4.24 (s, 2H), 3.83 (br s, 4H), 3.68 (s, 2H), 3.14 (br s, 4H). LCMS: Anal. Calcd. for C₁₃H₁₇NO₃: 235. found: 236 (M+H)⁺.

The following examples were similarly prepared using the method described for Cap-41:

Cap-42

LCMS: Anal. Calcd. for C₁₄H₁₉NO₂: 233; found: 234 (M + H)⁺. Cap-43

LCMS: Anal. Calcd. for C₁₃H₁₇NO₂: 219; found: 220 (M + H)⁺. Cap-44

LCMS: Anal. Calcd. for C₁₁H₁₅NO₂: 193; found: 194 (M + H)⁺. Cap-45

LCMS: Anal. Calcd. for C₁₄H₂₀N₂O₂: 248; found: 249 (M + H)⁺.

HMDS (1.85 mL, 8.77 mmol) was added to a suspension of (R)-2-amino-2-phenylacetic acid p-toluenesulfonate (2.83 g, 8.77 mmol) in CH₂Cl₂ (10 mL) and the mixture was stirred at room temperature for 30 minutes. Methyl isocyanate (0.5 g, 8.77 mmol) was added in one portion stirring continued for 30 minutes. The reaction was quenched by addition of H₂O (5 mL) and the resulting precipitate was filtered, washed with H₂O and n-hexanes, and dried under vacuum. (R)-2-(3-methylureido)-2-phenylacetic acid (1.5 g; 82%) was recovered as a white solid and it was used without further purification. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.54 (d, J=4.88 Hz, 3H) 5.17 (d, J=7.93 Hz, 1H) 5.95 (q, J=4.48 Hz, 1H) 6.66 (d, J=7.93 Hz, 1H) 7.26-7.38 (m, 5H) 12.67 (s, 1H). LCMS: Anal. Calcd. for C₁₀H₁₂N₂O₃ 208.08 found 209.121 (M+H)⁺; HPLC Phenomenex C-18 3.0×46 mm, 0 to 100% B over 2 minutes, 1 minute hold time, A=90% water, 10% methanol, 0.1% TFA, B=10% water, 90% methanol, 0.1% TFA, RT=1.38 min, 90% homogeneity index.

The desired product was prepared according to the method described for Cap-45a. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 0.96 (t, J=7.17 Hz, 3H) 2.94-3.05 (m, 2H) 5.17 (d, J=7.93 Hz, 1H) 6.05 (t, J=5.19 Hz, 1H) 6.60 (d, J=7.63 Hz, 1H) 7.26-7.38 (m, 5H) 12.68 (s, 1H). LCMS: Anal. Calcd. for C₁₁H₁₄N₂O₃ 222.10 found 223.15 (M+H)⁺. HPLC XTERRA C-18 3.0×506 mm, 0 to 100% B over 2 minutes, 1 minute hold time, A=90% water, 10% methanol, 0.2% H₃PO₄, B=10% water, 90% methanol, 0.2% H₃PO₄, RT=0.87 min, 90% homogeneity index.

Step 1; (R)-tert-butyl 2-(3,3-dimethylureido)-2-phenylacetate: To a stirred solution of (R)-tert-butyl-2-amino-2-phenylacetate (1.0 g, 4.10 mmol) and Hunig's base (1.79 mL, 10.25 mmol) in DMF (40 mL) was added dimethylcarbamoyl chloride (0.38 mL, 4.18 mmol) dropwise over 10 minutes. After stirring at room temperature for 3 hours, the reaction was concentrated under reduced pressure and the resulting residue was dissolved in ethyl acetate. The organic layer was washed with H₂O, 1N aq. HCl and brine, dried (MgSO₄), filtered and concentrated under reduced pressure. (R)-tert-butyl 2-(3,3-dimethylureido)-2-phenylacetate was obtained as a white solid (0.86 g; 75%) and used without further purification. ¹H NMR (500 MHz, DMSO-d₆) 8 ppm 1.33 (s, 9H) 2.82 (s, 6H) 5.17 (d, J=7.63 Hz, 1H) 6.55 (d, J=7.32 Hz, 1H) 7.24-7.41 (m, 5H). LCMS: Anal. Calcd. for C₁₅H₂₂N₂O₃ 278.16 found 279.23 (M+H)⁺; HPLC Phenomenex LUNA C-18 4.6×50 mm, 0 to 100% B over 4 minutes, 1 minute hold time, A=90% water, 10% methanol, 0.1% TFA, B=10% water, 90% methanol, 0.1% TFA, RT=2.26 min, 97% homogeneity index.

Step 2; (R)-2-(3,3-dimethylureido)-2-phenylacetic acid: To a stirred solution of ((R)-tert-butyl 2-(3,3-dimethylureido)-2-phenylacetate (0.86 g, 3.10 mmol) in CH₂Cl₂ (250 mL) was added TFA (15 mL) dropwise and the resulting solution was stirred at rt for 3 hours. The desired compound was then precipitated out of solution with a mixture of EtOAC:Hexanes (5:20), filtered off and dried under reduced pressure. (R)-2-(3,3-dimethylureido)-2-phenylacetic acid was isolated as a white solid (0.59 g, 86%) and used without further purification. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.82 (s, 6H) 5.22 (d, J=7.32 Hz, 1H) 6.58 (d, J=7.32 Hz, 1H) 7.28 (t, J=7.17 Hz, 1H) 7.33 (t, J=7.32 Hz, 2H) 7.38-7.43 (m, 2H) 12.65 (s, 1H). LCMS: Anal. Calcd. for C₁₁H₁₄N₂O₃: 222.24. found: 223.21 (M+H)⁺. HPLC XTERRA C-18 3.0×50 mm, 0 to 100% B over 2 minutes, 1 minute hold time, A=90% water, 10% methanol, 0.2% H₃PO₄, B=10% water, 90% methanol, 0.2% H₃PO₄, RT=0.75 min, 93% homogeneity index.

Step 1; (R)-tert-butyl 2-(3-cyclopentylureido)-2-phenylacetate: To a stirred solution of (R)-2-amino-2-phenylacetic acid hydrochloride (1.0 g, 4.10 mmol) and Hunig's base (1.0 mL, 6.15 mmol) in DMF (15 mL) was added cyclopentyl isocyanate (0.46 mL, 4.10 mmol) dropwise and over 10 minutes. After stirring at room temperature for 3 hours, the reaction was concentrated under reduced pressure and the resulting residue was taken up in ethyl acetate. The organic layer was washed with H₂O and brine, dried (MgSO₄), filtered, and concentrated under reduced pressure. (R)-tert-butyl 2-(3-cyclopentylureido)-2-phenylacetate was obtained as an opaque oil (1.32 g; 100%) and used without further purification. ¹H NMR (500 MHz, CD₃Cl-D) δ ppm 1.50-1.57 (m, 2H) 1.58-1.66 (m, 2H) 1.87-1.97 (m, 2H) 3.89-3.98 (m, 1H) 5.37 (s, 1H) 7.26-7.38 (m, 5H). LCMS: Anal. Calcd. for C₁₈H₂₆N₂O₃ 318.19 found 319.21 (M+H)⁺; HPLC XTERRA C-18 3.0×50 mm, 0 to 100% B over 4 minutes, 1 minute hold time, A=90% water, 10% methanol, 0.1% TFA, B=10% water, 90% methanol, 0.1% TFA, RT=2.82 min, 96% homogeneity index.

Step 2; (R)-2-(3-cyclopentylureido)-2-phenylacetic acid: To a stirred solution of (R)-tert-butyl 2-(3-cyclopentylureido)-2-phenylacetate (1.31 g, 4.10 mmol) in CH₂Cl₂ (25 mL) was added TFA (4 mL) and triethylsilane (1.64 mL; 10.3 mmol) dropwise, and the resulting solution was stirred at room temperature for 6 hours. The volatile components were removed under reduced pressure and the crude product was recrystallized in ethyl acetate/pentanes to yield (R)-2-(3-cyclopentylureido)-2-phenylacetic acid as a white solid (0.69 g, 64%). ¹H NMR (500 MHz, DMSO-d₆)δ ppm 1.17-1.35 (m, 2H) 1.42-1.52 (m, 2H) 1.53-1.64 (m, 2H) 1.67-1.80 (m, 2H) 3.75-3.89 (m, 1H) 5.17 (d, J=7.93 Hz, 1H) 6.12 (d, J=7.32 Hz, 1H) 6.48 (d, J=7.93 Hz, 1H) 7.24-7.40 (m, 5H) 12.73 (s, 1H). LCMS: Anal. Calcd. for C₁₄H₁₈N₂O₃: 262.31. found: 263.15 (M+H)⁺. HPLC XTERRA C-18 3.0×50 mm, 0 to 100% B over 2 minutes, 1 minute hold time, A=90% water, 10% methanol, 0.2% H₃PO₄, B=10% water, 90% methanol, 0.2% H₃PO₄, RT=1.24 min, 100% homogeneity index.

To a stirred solution of 2-(benzylamino)acetic acid (2.0 g, 12.1 mmol) in formic acid (91 mL) was added formaldehyde (6.94 mL, 93.2 mmol). After five hours at 70° C., the reaction mixture was concentrated under reduced pressure to 20 mL and a white solid precipitated. Following filtration, the mother liquors were collected and further concentrated under reduced pressure providing the crude product. Purification by reverse-phase preparative HPLC (Xterra 30×100 mm, detection at 220 nm, flow rate 35 mL/min, 0 to 35% B over 8 min; A=90% water, 10% methanol, 0.1% TFA, B=10% water, 90% methanol, 0.1% TFA) provided the title compound 2-(benzyl(methyl)-amino)acetic acid as its TFA salt (723 mg, 33%) as a colorless wax. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 2.75 (s, 3H) 4.04 (s, 2H) 4.34 (s, 2H) 7.29-7.68 (m, 5H). LCMS: Anal. Calcd. for: C₁₀H₁₃NO₂ 179.09. Found: 180.20 (M+H)⁺.

To a stirred solution of 3-methyl-2-(methylamino)butanoic acid (0.50 g, 3.81 mmol) in water (30 mL) was added K₂CO₃ (2.63 g, 19.1 mmol) and benzyl chloride (1.32 g, 11.4 mmol). The reaction mixture was stirred at ambient temperature for 18 hours. The reaction mixture was extracted with ethyl acetate (30 mL×2) and the aqueous layer was concentrated under reduced pressure providing the crude product which was purified by reverse-phase preparative HPLC (Xterra 30×100 mm, detection at 220 nm, flow rate 40 mL/min, 20 to 80% B over 6 min; A=90% water, 10% methanol, 0.1% TFA, B=10% water, 90% methanol, 0.1% TFA) to provide 2-(benzyl(methyl)amino)-3-methylbutanoic acid, TFA salt (126 mg, 19%) as a colorless wax. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 0.98 (d, 3H) 1.07 (d, 3H) 2.33-2.48 (m, 1H) 2.54-2.78 (m, 3H) 3.69 (s, 1H) 4.24 (s, 2H) 7.29-7.65 (m, 5H). LCMS: Anal. Calcd. for: C₁₃H₁₉NO₂ 221.14. Found: 222.28 (M+H)⁺.

Na₂CO₃ (1.83 g, 17.2 mmol) was added to NaOH (33 mL of 1M/H₂O, 33 mmol) solution of L-valine (3.9 g, 33.29 mmol) and the resulting solution was cooled with ice-water bath. Methyl chloroformate (2.8 mL, 36.1 mmol) was added dropwise over 15 min, the cooling bath was removed and the reaction mixture was stirred at ambient temperature for 3.25 hr. The reaction mixture was washed with ether (50 mL, 3×), and the aqueous phase was cooled with ice-water bath and acidified with concentrated HCl to a pH region of 1-2, and extracted with CH₂Cl₂ (50 mL, 3×). The organic phase was dried (MgSO₄) and evaporated in vacuo to afford Cap-51 as a white solid (6 g). ¹H NMR for the dominant rotamer (DMSO-d₅, δ=2.5 ppm, 500 MHz): 12.54 (s, 1H), 7.33 (d, J=8.6, 1H), 3.84 (dd, J=8.4, 6.0, 1H), 3.54 (s, 3H), 2.03 (m, 1H), 0.87 (m, 6H). HRMS: Anal. Calcd. for [M+H]⁺ C₇H₁₄NO₄: 176.0923. found 176.0922.

DIEA (137.5 mL, 0.766 mol) was added to a suspension of (S)-tent-butyl 2-amino-3-methylbutanoate hydrochloride (75.0 g, 0.357 mol) in THF (900 mL), and the mixture was cooled to 0° C. (ice/water bath). Methyl chloroformate (29.0 mL, 0.375 mol) was added dropwise over 45 min, the cooling bath was removed and the heterogeneous mixture was stirred at ambient temperature for 3 h. The solvent was removed under diminished pressure and the residue partitioned between EtOAc and water (1 L each). The organic layer was washed with H₂O (1 L) and brine (1 L), dried (MgSO₄), filtered and concentrated under diminished pressure. The crude material was passed through a plug of silica gel (1 kg), eluting with hexanes (4 L) and 15:85 EtOAc/hexanes (4 L) to afford (S)-tert-butyl 2-(methoxycarbonylamino)-3-methylbutanoate as a clear oil (82.0 g, 99% yield). ¹H-NMR (500 MHz, DMSO-d₆, δ=2.5 ppm) 7.34 (d, J=8.6, 1H), 3.77 (dd, J=8.6, 6.1, 1H), 3.53 (s, 3H), 1.94-2.05 (m, 1H), 1.39 (s, 9H), 0.83-0.92 (m, 6H). ¹³C-NMR (126 MHz, DMSO-d₆, δ=39.2 ppm) 170.92, 156.84, 80.38, 60.00, 51.34, 29.76, 27.62, 18.92, 17.95. LC/MS: [M+Na]⁺254.17.

Trifluoroacetic acid (343 mL, 4.62 mol) and Et₃SiH (142 mL, 0.887 mol) were added sequentially to a solution of (S)-tert-butyl 2-(methoxycarbonylamino)-3-methylbutanoate (82.0 g, 0.355 mol) in CH₂Cl₂ (675 mL), and the mixture was stirred at ambient temperature for 4 h. The volatile component was removed under diminished pressure and the resultant oil triturated with petroleum ether (600 mL) to afford a white solid, which was filtered and washed with hexanes (500 mL) and petroleum ether (500 mL). Recrystallization from EtOAc/petroleum ether afforded Cap-51 as white flaky crystals (54.8 g, 88% yield). MP=108.5-109.5° C. ¹H NMR (500 MHz, DMSO-d₆, δ=2.5 ppm) 12.52 (s, 1H), 7.31 (d, J=8.6, 1H), 3.83 (dd, J=8.6, 6.1, 1H), 3.53 (s, 3H), 1.94-2.07 (m, 1H), 0.86 (dd, J=8.9, 7.0, 6H). ¹³C NMR (126 MHz, DMSO-d₆, δ=39.2 ppm) 173.30, 156.94, 59.48, 51.37, 29.52, 19.15, 17.98. LC/MS: [M+H]⁺=176.11. Anal. Calcd. for C₇H₁₃NO₄: C, 47.99; H, 7.48; N, 7.99. Found: C, 48.17; H, 7.55; N, 7.99. Optical Rotation: [α]_(D)=−4.16 (12.02 mg/mL; MeOH). Optical purity: >99.5% ee. Note: the optical purity assessment was made on the methyl ester derivative of Cap-51, which was prepared under a standard TMSCHN₂ (benzene/MeOH) esterification protocol. HPLC analytical conditions: column, ChiralPak AD-H (4.6×250 mm, 5 μm); solvent, 95% heptane/5% IPA (isocratic); flow rate, 1 mL/min; temperature, 35° C.; UV monitored at 205 nm.

[Note: Cap 51 could also be purchased from Flamm.].

Cap-52 was synthesized from L-alanine according to the procedure described for the synthesis of Cap-51. For characterization purposes, a portion of the crude material was purified by a reverse phase HPLC (H₂O/methanol/TFA) to afford Cap-52 as a colorless viscous oil. ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): 12.49 (br s, 1H), 7.43 (d, J=7.3, 0.88H), 7.09 (app br s, 0.12H), 3.97 (m, 1H), 3.53 (s, 3H), 1.25 (d, J=7.3, 3H).

Cap-53 to −64 were prepared from appropriate starting materials according to the procedure described for the synthesis of Cap-51, with noted modifications if any.

Cap Structure Data Cap-53a: (R) Cap-53b: (S)

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 12.51 (br s, 1H), 7.4 (d, J = 7.9, 0.9H), 7.06 (app s, 0.1H), 3.86-3.82 (m, 1H), 3.53 (s, 3H), 1.75-1.67 (m, 1H), 1.62- 1.54 (m, 1H), 0.88 (d, J = 7.3, 3H). RT = 0.77 minutes (Cond. 2); LC/MS: Anal. Calcd. for [M + Na]⁺ C₆H₁₁NNaO₄: 184.06; found 184.07. HRMS Calcd. for [M + Na]⁺ C₆H₁₁NNaO₄: 184.0586; found 184.0592. Cap-54a: (R) Cap-54b: (S)

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 12.48 (s, 1H), 7.58 (d, J = 7.6, 0.9H), 7.25 (app s, 0.1H), 3.52 (s, 3H), 3.36-3.33 (m, 1H), 1.10-1.01 (m, 1H), 0.54-0.49 (m, 1H), 0.46-0.40 (m, 1H), 0.39-0.35 (m, 1H), 0.31-0.21 (m, 1H). HRMS Calcd. for [M + H]⁺ C₇H₁₂NO₄: 174.0766; found 174.0771 Cap-55

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 12.62 (s, 1H), 7.42 (d, J = 8.2, 0.9H), 7.07 (app s, 0.1H), 5.80-5.72 (m, 1H), 5.10 (d, J = 17.1, 1H), 5.04 (d, J = 10.4, 1H), 4.01-3.96 (m, 1H), 3.53 (s, 3H), 2.47-2.42 (m, 1H), 2.35-2.29 (m, 1H). Cap-56

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 12.75 (s, 1H), 7.38 (d, J = 8.3, 0.9H), 6.96 (app s, 0.1H), 4.20-4.16 (m, 1H), 3.60-3.55 (m, 2H), 3.54 (s, 3H), 3.24 (s, 3H). Cap-57

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 12.50 (s, 1H), 8.02 (d, J = 7.7, 0.08H), 7.40 (d, J = 7.9, 0.76H), 7.19 (d, J = 8.2, 0.07H), 7.07 (d, J = 6.7, 0.09H), 4.21-4.12.(m, 0.08H), 4.06-3.97 (m, 0.07H), 3.96-3.80 (m, 0.85H), 3.53 (s, 3H), 1.69-1.51 (m, 2H), 1.39-1.26 (m, 2H), 0.85 (t, J = 7.4, 3H). LC (Cond. 2): RT = 1.39 LC/MS: Anal. Calcd. for [M +  H]⁺ C₇H₁₄NO₄: 176.09; found 176.06. Cap-58

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 12.63 (br s, 1H), 7.35 (s,1H), 7.31 (d, J = 8.2, 1H), 6.92 (s, 1H), 4.33-4.29 (m, 1H), 3.54 (s, 3H), 2.54 (dd, J = 15.5, 5.4, 1H), 2.43 (dd, J = 15.6, 8.0, 1H). RT = 0.16 min (Cond. 2); LC/MS: Anal. Calcd. for [M + H]⁺ C₆H₁₁N₂O₅: 191.07; found 191.14. Cap-59a: (R) Cap-59b: (S)

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): δ 12.49 (br s, 1H), 7.40 (d, J = 7.3, 0.89H), 7.04 (br s, 0.11H), 4.00-3.95 (m, 3H), 1.24 (d, J = 7.3, 3H), 1.15 (t, J = 7.2, 3H). HRMS: Anal. Calcd. for [M + H]⁺ C₆H₁₂NO₄: 162.0766; found 162.0771. Cap-60

The crude material was purified with a reverse phase HPLC (H₂O/MeOH/TFA) to afford a colorless viscous oil that crystallized to a white solid upon exposure to high vacuum. ¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): δ 12.38 (br s, 1H), 7.74 (s, 0.82H), 7.48 (s, 0.18H), 3.54/3.51 (two s, 3H), 1.30 (m, 2H), 0.98 (m, 2H). HRMS: Anal. Calcd. for [M +  H]⁺ C₆H₁₀NO₄: 160.0610; found 160.0604. Cap-61

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): δ 12.27 (br s, 1H), 7.40 (br s, 1H), 3.50 (s, 3H), 1.32 (s, 6H). HRMS: Anal. Calcd. for [M + H]⁺ C₆H₁₂NO₄: 162.0766; found 162.0765. Cap-62

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): δ 12.74 (br s, 1H), 4.21 (d, J = 10.3, 0.6H), 4.05 (d, J = 10.0, 0.4H), 3.62/3.60 (two singlets, 3H), 3.0 (s, 3H), 2.14-2.05 (m, 1H), 0.95 (d, J = 6.3, 3H), 0.81 (d, J = 6.6, 3H). LC/MS: Anal. Calcd. for [M − H]⁻ C₈H₁₄NO₄: 188.09; found 188.05. Cap-63

[Note: the reaction was allowed to run for longer than what was noted for the general procedure.] ¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): 12.21 (br s, 1H), 7.42 (br s, 1H), 3.50 (s, 3H), 2.02-1.85 (m, 4H), 1.66-1.58 (m, 4H). LC/MS: Anal. Calcd. for [M + H]⁺ C₈H₁₄NO₄: 188.09; found 188.19. Cap-64

[Note: the reaction was allowed to run for longer than what was noted for the general procedure.] ¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): 12.35 (br s, 1H), 7.77 (s, 0.82H), 7.56/7.52 (overlapping br s, 0.18H), 3.50 (s, 3H), 2.47-2.40 (m, 2H), 2.14-2.07 (m, 2H), 1.93-1.82 (m, 2H).

Methyl chloroformate (0.65 mL, 8.39 mmol) was added dropwise over 5 min to a cooled (ice-water) mixture of Na₂CO₃ (0.449 g, 4.23 mmol), NaOH (8.2 mL of 1M/H₂O, 8.2 mmol) and (S)-2-amino-3-hydroxy-3-methylbutanoic acid (1.04 g, 7.81 mmol). The reaction mixture was stirred for 45 min, and then the cooling bath was removed and stirring was continued for an additional 3.75 hr. The reaction mixture was washed with CH₂Cl₂, and the aqueous phase was cooled with ice-water bath and acidified with concentrated HCl to a pH region of 1-2. The volatile component was removed in vacuo and the residue was taken up in a 2:1 mixture of MeOH/CH₂Cl₂ (15 mL) and filtered, and the filterate was rotervaped to afford Cap-65 as a white semi-viscous foam (1.236 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 6.94 (d, J=8.5, 0.9H), 6.53 (br s, 0.1H), 3.89 (d, J=8.8, 1H), 2.94 (s, 3H), 1.15 (s, 3H), 1.13 (s, 3H).

Cap-66 and -67 were prepared from appropriate commercially available starting materials by employing the procedure described for the synthesis of Cap-65.

¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 12.58 (br s, 1H), 7.07 (d, J=8.3, 0.13H), 6.81 (d, J=8.8, 0.67H), 4.10-4.02 (m, 1.15H), 3.91 (dd, J=9.1, 3.5, 0.85H), 3.56 (s, 3H), 1.09 (d, J=6.2, 3H). [Note: only the dominant signals of NH were noted].

¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): 12.51 (br s, 1H), 7.25 (d, J=8.4, 0.75H), 7.12 (br d, J=0.4, 0.05H), 6.86 (br s, 0.08H), 3.95-3.85 (m, 2H), 3.54 (s, 3H), 1.08 (d, J=6.3, 3H). [Note: only the dominant signals of NH were noted].

Methyl chloroformate (0.38 ml, 4.9 mmol) was added drop-wise to a mixture of 1N NaOH (aq) (9.0 ml, 9.0 mmol), 1M NaHCO₃ (aq) (9.0 ml, 9.0 mol), L-aspartic acid β-benzyl ester (1.0 g, 4.5 mmol) and Dioxane (9 ml). The reaction mixture was stirred at ambient conditions for 3 hr, and then washed with Ethyl acetate (50 ml, 3×). The aqueous layer was acidified with 12N HCl to a pH ˜1-2, and extracted with ethyl acetate (3×50 ml). The combined organic layers were washed with brine, dried (Na₂SO₄), filtered, and concentrated in vacuo to afford Cap-68 as a light yellow oil (1.37 g; mass is above theoretical yield, and the product was used without further purification). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): δ 12.88 (br s, 1H), 7.55 (d, J=8.5, 1H), 7.40-7.32 (m, 5H), 5.13 (d, J=12.8, 1H), 5.10 (d, J=12.9, 1H), 4.42-4.38 (m, 1H), 3.55 (s, 3H), 2.87 (dd, J=16.2, 5.5, 1H), 2.71 (dd, J=16.2, 8.3, 1H). LC (Cond. 2): RT=1.90 min; LC/MS: Anal. Calcd. For [M+H]⁺ C₁₃H₁₆NO₆: 282.10. found 282.12.

NaCNBH₃ (2.416 g, 36.5 mmol) was added in batches to a chilled (˜15° C.) water (17 mL)/MeOH (10 mL) solution of alanine (1.338 g, 15.0 mmol). A few minutes later acetaldehyde (4.0 mL, 71.3 mmol) was added drop-wise over 4 min, the cooling bath was removed, and the reaction mixture was stirred at ambient condition for 6 hr. An additional acetaldehyde (4.0 mL) was added and the reaction was stirred for 2 hr. Concentrated HCl was added slowly to the reaction mixture until the pH reached ˜1.5, and the resulting mixture was heated for 1 hr at 40° C. Most of the volatile component was removed in vacuo and the residue was purified with a Dowex® 50WX8-100 ion-exchange resin (column was washed with water, and the compound was eluted with dilute NH₄OH, prepared by mixing 18 ml of NH₄OH and 282 ml of water) to afford Cap-69 (2.0 g) as an off-white soft hygroscopic solid. ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 3.44 (q, J=7.1, 1H), 2.99-2.90 (m, 2H), 2.89-2.80 (m, 2H), 1.23 (d, J=7.1, 3H), 1.13 (t, J=7.3, 6H).

Cap-70 to −74x were prepared according to the procedure described for the synthesis of Cap-69 by employing appropriate starting materials.

Cap-70a: (R) Cap-70b: (S)

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): δ 3.42 (q, J = 7.1, 1H), 2.68-2.60 (m, 4H), 1.53-1.44 (m, 4H), 1.19 (d, J = 7.3, 3H), 0.85 (t, J = 7.5, 6H). LC/MS: Anal. Calcd. for [M + H]⁺ C₉H₂₀NO₂: 174.15; found 174.13. Cap-71a: (R) Cap-71b: (S)

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 3.18-3.14 (m, 1H), 2.84-2.77 (m, 2H), 2.76-2.68 (m, 2H), 1.69-1.54 (m, 2H), 1.05 (t, J = 7.2, 6H), 0.91 (t, J = 7.3, 3H). LC/MS: Anal. Calcd. for [M + H]⁺ C₈H₁₈NO₂: 160.13; found 160.06. Cap-72

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 400 MHz): δ 2.77-2.66 (m, 3H), 2.39-2.31 (m, 2H), 1.94-1.85 (m, 1H), 0.98 (t, J = 7.1, 6H), 0.91 (d, J = 6.5, 3H), 0.85 (d, J = 6.5, 3H). LC/MS: Anal. Calcd. for [M + H]⁺ C₉H₂₀NO₂: 174.15; found 174.15. Cap-73

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 9.5 (br s, 1H), 3.77 (dd, J = 10.8, 4.1, 1H), 3.69-3.61 (m, 2H), 3.26 (s, 3H), 2.99-2.88 (m, 4H), 1.13 (t, J = 7.2, 6H). Cap-74

¹H NMR (DMSO-d₆, δ = 2.5 ppm, 500 MHz): δ 3.54 (s, 1H), 6.89 (s, 1H), 3.81 (t, J = 6.6, k, 1H), 2.82-2.71 (m, 4H), 2.63 (dd, J = 15.6, 7.0, 1H), 2.36 (dd, J = 15.4, 6.3, 1H), 1.09 (t, J = 7.2, 6H). RT = 0.125 minutes (Cond. 2); LC/MS: Anal. Calcd. for [M + H]⁺ C₈H₁₇N₂O₃: 189.12; found 189.13. Cap-74x

LC/MS: Anal. Calcd. for [M + H]⁺ C₁₀H₂₂NO₂: 188.17; found 188.21

NaBH₃CN (1.6 g, 25.5 mmol) was added to a cooled (ice/water bath) water (25 ml)/methanol (15 ml) solution of H-D-Ser-OBzl HCl (2.0 g, 8.6 mmol). Acetaldehyde (1.5 ml, 12.5 mmol) was added drop-wise over 5 min, the cooling bath was removed, and the reaction mixture was stirred at ambient condition for 2 hr. The reaction was carefully quenched with 12N HCl and concentrated in vacuo. The residue was dissolved in water and purified with a reverse phase HPLC (MeOH/H₂O/TFA) to afford the TFA salt of (R)-benzyl 2-(diethylamino)-3-hydroxypropanoate as a colorless viscous oil (1.9 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): δ 9.73 (br s, 1H), 7.52-7.36 (m, 5H), 5.32 (d, J=12.2, 1H), 5.27 (d, J=12.5, 1H), 4.54-4.32 (m, 1H), 4.05-3.97 (m, 2H), 3.43-3.21 (m, 4H), 1.23 (t, J=7.2, 6H). LC/MS (Cond. 2): RT=1.38 min; LC/MS: Anal. Calcd. for [M+H]⁺ C₁₄H₂₂NO₃: 252.16. found 252.19.

Cap-75

NaH (0.0727 g, 1.82 mmol, 60%) was added to a cooled (ice-water) THF (3.0 mL) solution of the TFA salt (R)-benzyl 2-(diethylamino)-3-hydroxypropanoate (0.3019 g, 0.8264 mmol) prepared above, and the mixture was stirred for 15 min. Methyl iodide (56 μL, 0.90 mmol) was added and stirring was continued for 18 hr while allowing the bath to thaw to ambient condition. The reaction was quenched with water and loaded onto a MeOH pre-conditioned MCX (6 g) cartridge, and washed with methanol followed by compound elution with 2N NH₃/Methanol. Removal of the volatile component in vacuo afforded Cap-75, contaminated with (R)-2-(diethylamino)-3-hydroxypropanoic acid, as a yellow semi-solid (100 mg). The product was used as is without further purification.

NaCNBH₃ (1.60 g, 24.2 mmol) was added in batches to a chilled (˜15° C.) water/MeOH (12 mL each) solution of (S)-4-amino-2-(tert-butoxycarbonylamino) butanoic acid (2.17 g, 9.94 mmol). A few minutes later acetaldehyde (2.7 mL, 48.1 mmol) was added drop-wise over 2 min, the cooling bath was removed, and the reaction mixture was stirred at ambient condition for 3.5 hr. An additional acetaldehyde (2.7 mL, 48.1 mmol) was added and the reaction was stirred for 20.5 hr. Most of the MeOH component was removed in vacuo, and the remaining mixture was treated with concentrated HCl until its pH reached ˜1.0 and then heated for 2 hr at 40° C. The volatile component was removed in vacuo, and the residue was treated with 4 M HCl/dioxane (20 mL) and stirred at ambient condition for 7.5 hr. The volatile component was removed in vacuo and the residue was purified with Dowex® 50WX8-100 ion-exchange resin (column was washed with water and the compound was eluted with dilute NH₄OH, prepared from 18 ml of NH₄OH and 282 ml of water) to afford intermediate (S)-2-amino-4-(diethylamino)butanoic acid as an off-white solid (1.73 g).

Methyl chloroformate (0.36 mL, 4.65 mmol) was added drop-wise over 11 min to a cooled (ice-water) mixture of Na₂CO₃ (0.243 g, 2.29 mmol), NaOH (4.6 mL of 1M/H₂O, 4.6 mmol) and the above product (802.4 mg). The reaction mixture was stirred for 55 min, and then the cooling bath was removed and stirring was continued for an additional 5.25 hr. The reaction mixture was diluted with equal volume of water and washed with CH₂Cl₂ (30 mL, 2×), and the aqueous phase was cooled with ice-water bath and acidified with concentrated HCl to a pH region of 2. The volatile component was then removed in vacuo and the crude material was free-based with MCX resin (6.0 g; Column was washed with water, and sample was eluted with 2.0 M NH₃/MeOH) to afford impure Cap-76 as an off-white solid (704 mg). ¹H NMR (MeOH-d₄, S=3.29 ppm, 400 MHz): δ 3.99 (dd, J=7.5, 4.7, 1H), 3.62 (s, 3H), 3.25-3.06 (m, 6H), 2.18-2.09 (m, 1H), 2.04-1.96 (m, 1H), 1.28 (t, J=7.3, 6H). LC/MS: Anal. Calcd. for [M+H]⁺C₁₀H₂₁N₂O₄: 233.15. found 233.24.

The synthesis of Cap-77 was conducted according to the procedure described for Cap-7 by using 7-azabicyclo[2.2.1]heptane for the SN₂ displacement step, and by effecting the enantiomeric separation of the intermediate benzyl 2-(7-azabicyclo[2.2.1]heptan-7-yl)-2-phenylacetate using the following condition: the intermediate (303.7 mg) was dissolved in ethanol, and the resulting solution was injected on a chiral HPLC column (Chiracel AD-H column, 30×250 mm, 5 um) eluting with 90% CO₂-10% EtOH at 70 mL/min, and a temperature of 35° C. to provide 124.5 mg of enantiomer-1 and 133.8 mg of enantiomer-2. These benzyl esters were hydrogenolysed according to the preparation of Cap-7 to provide Cap-77: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 7.55 (m, 2H), 7.38-7.30 (m, 3H), 4.16 (s, 1H), 3.54 (app br s, 2H), 2.08-1.88 (m, 4H), 1.57-1.46 (m, 4H). LC (Cond. 1): RT=0.67 min; LC/MS: Anal. Calcd. for [M+H]⁺C₁₄H₁₈NO₂: 232.13. found 232.18. HRMS: Anal. Calcd. for [M+H]⁺C₁₄H₁₈NO₂: 232.1338. found 232.1340.

NaCNBH₃ (0.5828 g, 9.27 mmol) was added to a mixture of the HCl salt of (R)-2-(ethylamino)-2-phenylacetic acid (an intermediate in the synthesis of Cap-3; 0.9923 mg, 4.60 mmol) and (1-ethoxycyclopropoxy)trimethylsilane (1.640 g, 9.40 mmol) in MeOH (10 mL), and the semi-heterogeneous mixture was heated at 50° C. with an oil bath for 20 hr. More (1-ethoxycyclopropoxy)trimethylsilane (150 mg, 0.86 mmol) and NaCNBH₃ (52 mg, 0.827 mmol) were added and the reaction mixture was heated for an additional 3.5 hr. It was then allowed to cool to ambient temperature and acidified to a ˜pH region of 2 with concentrated HCl, and the mixture was filtered and the filtrate was rotervaped. The resulting crude material was taken up in i-PrOH (6 mL) and heated to effect dissolution, and the non-dissolved part was filtered off and the filtrate concentrated in vacuo. About ⅓ of the resultant crude material was purified with a reverse phase HPLC (H₂O/MeOH/TFA) to afford the TFA salt of Cap-78 as a colorless viscous oil (353 mg). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz; after D₂O exchange): δ 7.56-7.49 (m, 5H), 5.35 (S, 1H), 3.35 (m, 1H), 3.06 (app br s, 1H), 2.66 (m, 1H), 1.26 (t, J=7.3, 3H), 0.92 (m, 1H), 0.83-0.44 (m, 3H). LC (Cond. 1): RT=0.64 min; LC/MS: Anal. Calcd. for [M+H]⁺ C₁₃H₁₈NO₂: 220.13. found 220.21. HRMS: Anal. Calcd. for [M+H]⁺C₁₃H₁₈NO₂: 220.1338. found 220.1343.

Ozone was bubbled through a cooled (−78° C.) CH₂Cl₂ (5.0 mL) solution Cap-55 (369 mg, 2.13 mmol) for about 50 min until the reaction mixture attained a tint of blue color. Me₂S (10 pipet drops) was added, and the reaction mixture was stirred for 35 min. The −78° C. bath was replaced with a −10° C. bath and stirring continued for an additional 30 min, and then the volatile component was removed in vacuo to afford a colorless viscous oil.

NaBH₃CN (149 mg, 2.25 mmol) was added to a MeOH (5.0 mL) solution of the above crude material and morpholine (500 μL, 5.72 mmol) and the mixture was stirred at ambient condition for 4 hr. It was cooled to ice-water temperature and treated with concentrated HCl to bring its pH to ˜2.0, and then stirred for 2.5 hr. The volatile component was removed in vacuo, and the residue was purified with a combination of MCX resin (MeOH wash; 2.0 N NH₃/MeOH elution) and a reverse phase HPLC (H₂O/MeOH/TFA) to afford Cap-79 containing unknown amount of morpholine.

In order to consume the morpholine contaminant, the above material was dissolved in CH₂Cl₂ (1.5 mL) and treated with Et₃N (0.27 mL, 1.94 mmol) followed by acetic anhydride (0.10 mL, 1.06 mmol) and stirred at ambient condition for 18 hr. THF (1.0 mL) and H₂O (0.5 mL) were added and stirring continued for 1.5 hr. The volatile component was removed in vacuo, and the resultant residue was passed through MCX resin (MeOH wash; 2.0 N NH₃/MeOH elution) to afford impure Cap-79 as a brown viscous oil, which was used for the next step without further purification.

SOCl₂ (6.60 mL, 90.5 mmol) was added drop-wise over 15 min to a cooled (ice-water) mixture of (S)-3-amino-4-(benzyloxy)-4-oxobutanoic acid (10.04 g, 44.98 mmol) and MeOH (300 mL), the cooling bath was removed and the reaction mixture was stirred at ambient condition for 29 hr. Most of the volatile component was removed in vacuo and the residue was carefully partitioned between EtOAc (150 mL) and saturated NaHCO₃ solution. The aqueous phase was extracted with EtOAc (150 mL, 2×), and the combined organic phase was dried (MgSO₄), filtered, and concentrated in vacuo to afford (S)-1-benzyl 4-methyl 2-aminosuccinate as a colorless oil (9.706 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 7.40-7.32 (m, 5H), 5.11 (s, 2H), 3.72 (app t, J=6.6, 1H), 3.55 (s, 3H), 2.68 (dd, J=15.9, 6.3, 1H), 2.58 (dd, J=15.9, 6.8, 1H), 1.96 (s, 2H). LC (Cond. 1): RT=0.90 min; LC/MS: Anal. Calcd. for [M+H]⁺C₁₂H₁₆NO₄: 238.11. found 238.22.

Pb(NO₃)₂ (6.06 g, 18.3 mmol) was added over 1 min to a CH₂Cl₂ (80 mL) solution of (S)-1-benzyl 4-methyl 2-aminosuccinate (4.50 g, 19.0 mmol), 9-bromo-9-phenyl-9H-fluorene (6.44 g, 20.0 mmol) and Et₃N (3.0 mL, 21.5 mmol), and the heterogeneous mixture was stirred at ambient condition for 48 hr. The mixture was filtered and the filtrate was treated with MgSO₄ and filtered again, and the final filtrate was concentrated. The resulting crude material was submitted to a Biotage purification (350 g silica gel, CH₂Cl₂ elution) to afford (S)-1-benzyl 4-methyl 2-(9-phenyl-9H-fluoren-9-ylamino)succinate as highly viscous colorless oil (7.93 g). NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): δ 7.82 (m, 2H), 7.39-7.13 (m, 16H), 4.71 (d, J=12.4, 1H), 4.51 (d, J=12.6, 1H), 3.78 (d, J=9.1, NH), 3.50 (s, 3H), 2.99 (m, 1H), 2.50-2.41 (m, 2H, partially overlapped with solvent). LC (Cond. 1): RT=2.16 min; LC/MS: Anal. Calcd. for [M+H]⁺C₃₁H₂₈NO₄: 478.20. found 478.19.

LiHMDS (9.2 mL of 1.0 M/THF, 9.2 mmol) was added drop-wise over 10 min to a cooled (−78° C.) THF (50 mL) solution of (S)-1-benzyl 4-methyl 2-(9-phenyl-9H-fluoren-9-ylamino)succinate (3.907 g, 8.18 mmol) and stirred for ˜1 hr. MeI (0.57 mL, 9.2 mmol) was added drop-wise over 8 min to the mixture, and stirring was continued for 16.5 hr while allowing the cooling bath to thaw to room temperature. After quenching with saturated NH₄Cl solution (5 mL), most of the organic component was removed in vacuo and the residue was partitioned between CH₂Cl₂ (100 mL) and water (40 mL). The organic layer was dried (MgSO₄), filtered, and concentrated in vacuo, and the resulting crude material was purified with a Biotage (350 g silica gel; 25% EtOAc/hexanes) to afford 3.65 g of a 2S/3S and 2S/3R diastereomeric mixtures of 1-benzyl 4-methyl 3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)succinate in ˜1.0:0.65 ratio (¹H NMR). The stereochemistry of the dominant isomer was not determined at this juncture, and the mixture was submitted to the next step without separation. Partial ¹H NMR data (DMSO-d₆, δ=2.5 ppm, 400 MHz): major diastereomer, δ 4.39 (d, J=12.3, 1H of CH₂), 3.33 (s, 3H, overlapped with H₂O signal), 3.50 (d, J=10.9, NH), 1.13 (d, J=7.1, 3H); minor diastereomer, δ 4.27 (d, J=12.3, 1H of CH₂), 3.76 (d, J=10.9, NH), 3.64 (s, 3H), 0.77 (d, J=7.0, 3H). LC (Cond. 1): RT=2.19 min; LC/MS: Anal. Calcd. for [M+H]⁺C₃₂H₃₀NO₄: 492.22. found 492.15.

Diisobutylaluminum hydride (20.57 ml of 1.0 M in hexanes, 20.57 mmol) was added drop-wise over 10 min to a cooled (−78° C.) THF (120 mL) solution of (2S)-1-benzyl 4-methyl 3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)succinate (3.37 g, 6.86 mmol) prepared above, and stirred at −78° C. for 20 hr. The reaction mixture was removed from the cooling bath and rapidly poured into ˜1M H₃PO₄/H₂O (250 mL) with stirring, and the mixture was extracted with ether (100 mL, 2×). The combined organic phase was washed with brine, dried (MgSO₄), filtered and concentrated in vacuo. A silica gel mesh of the crude material was prepared and submitted to chromatography (25% EtOAc/hexanes; gravity elution) to afford 1.1 g of (2S,3S)-benzyl 4-hydroxy-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate, contaminated with benzyl alcohol, as a colorless viscous oil and (2S,3R)-benzyl 4-hydroxy-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate containing the (2S,3R) stereoisomer as an impurity. The later sample was resubmitted to the same column chromatography purification conditions to afford 750 mg of purified material as a white foam. [Note: the (2S,3S) isomer elutes before the (2S,3R) isomer under the above condition]. (2S,3S) isomer: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): 7.81 (m, 2H), 7.39-7.08 (m, 16H), 4.67 (d, J=12.3, 1H), 4.43 (d, J=12.4, 1H), 4.21 (app t, J=5.2, OH), 3.22 (d, J=10.1, NH), 3.17 (m, 1H), 3.08 (m, 1H), ˜2.5 (m, 1H, overlapped with the solvent signal), 1.58 (m, 1H), 0.88 (d, J=6.8, 3H). LC (Cond. 1): RT=2.00 min; LC/MS: Anal. Calcd. for [M+H]⁺ C₃₁H₃₀NO₃: 464.45. found 464.22. (2S,3R) isomer: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz): 7.81 (d, J=7.5, 2H), 7.39-7.10 (m, 16H), 4.63 (d, J=12.1, 1H), 4.50 (app t, J=4.9, 1H), 4.32 (d, J=12.1, 1H), 3.59-3.53 (m, 2H), 3.23 (m, 1H), 2.44 (dd, J=9.0, 8.3, 1H), 1.70 (m, 1H), 0.57 (d, J=6.8, 3H). LC (Cond. 1): RT=1.92 min; LC/MS: Anal. Calcd. for [M+H]⁺C₃₁H₃₀NO₃: 464.45. found 464.52.

The relative stereochemical assignments of the DIBAL-reduction products were made based on NOE studies conducted on lactone derivatives prepared from each isomer by employing the following protocol: LiHMDS (50 μL of 1.0 M/THF, 0.05 mmol) was added to a cooled (ice-water) THF (2.0 mL) solution of (2S,3S)-benzyl 4-hydroxy-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate (62.7 mg, 0.135 mmol), and the reaction mixture was stirred at similar temperature for ˜2 hr. The volatile component was removed in vacuo and the residue was partitioned between CH₂Cl₂ (30 mL), water (20 mL) and saturated aqueous NH₄Cl solution (1 mL). The organic layer was dried (MgSO₄), filtered, and concentrated in vacuo, and the resulting crude material was submitted to a Biotage purification (40 g silica gel; 10-15% EtOAc/hexanes) to afford (3S,4S)-4-methyl-3-(9-phenyl-9H-fluoren-9-ylamino)dihydrofuran-2(3H)-one as a colorless film of solid (28.1 mg). (2S,3R)-benzyl 4-hydroxy-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate was elaborated similarly to (3S,4R)-4-methyl-3-(9-phenyl-9H-fluoren-9-ylamino)dihydrofuran-2(3H)-one. (3S,4S)-lactone isomer: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz), 7.83 (d, J=7.5, 2H), 7.46-7.17 (m, 11H), 4.14 (app t, J=8.3, 1H), 3.60 (d, J=5.8, NH), 3.45 (app t, J=9.2, 1H), ˜2.47 (m, 1H, partially overlapped with solvent signal), 2.16 (m, 1H), 0.27 (d, J=6.6, 3H). LC (Cond. 1): RT=1.98 min; LC/MS: Anal. Calcd. for [M+Na]⁺C₂₄H₂₁NNaO₂: 378.15. found 378.42. (3S,4R)-lactone isomer: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz), 7.89 (d, J=7.6, 1H), 7.85 (d, J=7.3, 1H), 7.46-7.20 (m, 11H), 3.95 (dd, J=9.1, 4.8, 1H), 3.76 (d, J=8.8, 1H), 2.96 (d, J=3.0, NH), 2.92 (dd, J=6.8, 3, NCH), 1.55 (m, 1H), 0.97 (d, J=7.0, 3H). LC (Cond. 1): RT=2.03 min; LC/MS: Anal. Calcd. for [M+Na]⁺ C₂₄H₂₁NNaO₂: 378.15. found 378.49.

TBDMS-Cl (48 mg, 0.312 mmol) followed by imidazole (28.8 mg, 0.423 mmol) were added to a CH₂Cl₂ (3 ml) solution of (2S,3S)-benzyl 4-hydroxy-3-s methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate (119.5 mg, 0.258 mmol), and the mixture was stirred at ambient condition for 14.25 hr. The reaction mixture was then diluted with CH₂Cl₂ (30 mL) and washed with water (15 mL), and the organic layer was dried (MgSO₄), filtered, and concentrated in vacuo. The resultant crude material was purified with a Biotage (40 g silica gel; 5% EtOAc/hexanes) to afford to (2S,3S)-benzyl 4-(tert-butyldimethylsilyloxy)-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate, contaminated with TBDMS based impurities, as a colorless viscous oil (124.4 mg). (2S,3R)-benzyl 4-hydroxy-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate was elaborated similarly to (2S,3R)-benzyl 4-(tert-butyldimethylsilyloxy)-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate. (2S,3S)-silyl ether isomer: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz), 7.82 (d, J=4.1, 1H), 7.80 (d, J=4.0, 1H), 7.38-7.07 (m, 16H), 4.70 (d, J=12.4, 1H), 4.42 (d, J=12.3, 1H), 3.28-3.19 (m, 3H), 2.56 (dd, J=10.1, 5.5, 1H), 1.61 (m, 1H), 0.90 (d, J=6.8, 3H), 0.70 (s, 9H), −0.13 (s, 3H), −0.16 (s, 3H). LC (Cond. 1, where the run time was extended to 4 min): RT=3.26 min; LC/MS: Anal. Calcd. for [M+H]⁺ C₃₇H₄₄NO₃Si: 578.31. found 578.40. (2S,3R)-silyl ether isomer: ¹H NMR (DMSO-d₆, S=2.5 ppm, 400 MHz), 7.82 (d, J=3.0, 1H), 7.80 (d, J=3.1, 1H), 7.39-7.10 (m, 16H), 4.66 (d, J=12.4, 1H), 4.39 (d, J=12.4, 1H), 3.61 (dd, J=9.9, 5.6, 1H), 3.45 (d, J=9.5, 1H), 3.41 (dd, J=10, 6.2, 1H), 2.55 (dd, J=9.5, 7.3, 1H), 1.74 (m, 1H), 0.77 (s, 9H), 0.61 (d, J=7.1, 3H), −0.06 (s; 3H), −0.08 (s, 3H).

A balloon of hydrogen was attached to a mixture of (2S,3S)-benzyl 4-(tert-butyldimethylsilyloxy)-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate (836 mg, 1.447 mmol) and 10% Pd/C. (213 mg) in EtOAc (16 mL) and the mixture was stirred at room temperature for ˜21 hr, where the balloon was recharged with H₂ as necessary. The reaction mixture was diluted with CH₂Cl₂ and filtered through a pad of diatomaceous earth (Celite-545®), and the pad was washed with EtOAc (200 mL), EtOAc/MeOH (1:1 mixture, 200 mL) and MeOH (750 mL). The combined organic phase was concentrated, and a silica gel mesh was prepared from the resulting crude material and submitted to a flash chromatography (8:2:1 mixture of EtOAc/i-PrOH/H₂O) to afford (2S,3S)-2-amino-4-(tert-butyldimethylsilyloxy)-3-methylbutanoic acid as a white fluffy solid (325 mg). (2S,3R)-benzyl 4-(tert-butyldimethylsilyloxy)-3-methyl-2-(9-phenyl-9H-fluoren-9-ylamino)butanoate was similarly elaborated to (2S,3R)-2-amino-4-(tert-butyldimethylsilyloxy)-3-methylbutanoic acid. (2S,3S)-amino acid isomer: ¹H NMR (Methanol-d₄, δ=3.29 ppm, 400 MHz), 3.76 (dd, J=10.5, 5.2, 1H), 3.73 (d, J=3.0, 1H), 3.67 (dd, J=10.5, 7.0, 1H), 2.37 (m, 1H), 0.97 (d, J=7.0, 3H), 0.92 (s, 9H), 0.10 (s, 6H). LC/MS: Anal. Calcd. for [M+H]⁺ C₁₁H₂₆NO₃Si: 248.17. found 248.44. (2S,3R)-amino acid isomer: ¹H NMR (Methanol-d₄, δ=3.29 ppm, 400 MHz), 3.76-3.75 (m, 2H), 3.60 (d, J=4.1, 1H), 2.16 (m, 1H), 1.06 (d, J=7.3, 3H), 0.91 (s, 9H), 0.09 (s, 6H). Anal. Calcd. for [M+H]⁺C₁₁H₂₆NO₃Si: 248.17. found 248.44.

Water (1 mL) and NaOH (0.18 mL of 1.0 M/H₂O, 0.18 mmol) were added to a mixture of (2S,3S)-2-amino-4-(tert-butyldimethylsilyloxy)-3-methylbutanoic acid (41.9 mg, 0.169 mmol) and Na₂CO₃ (11.9 mg, 0.112 mmol), and sonicated for about 1 min to effect dissolution of reactants. The mixture was then cooled with an ice-water bath, methyl chloroformate (0.02 mL, 0.259 mmol) was added over 30 s, and vigorous stirring was continued at similar temperature for 40 min and then at ambient temperature for 2.7 hr. The reaction mixture was diluted with water (5 mL), cooled with ice-water bath and treated drop-wise with 1.0 N HCl aqueous solution (˜0.23 mL). The mixture was further diluted with water (10 mL) and extracted with CH₂Cl₂ (15 mL, 2×). The combined organic phase was dried (MgSO₄), filtered, and concentrated in vacuo to afford Cap-80a as an off-white solid. (2S,3R)-2-amino-4-(tert-butyldimethylsilyloxy)-3-methylbutanoic acid was similarly elaborated to Cap-80b. Cap-80a: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 400 MHz), 12.57 (br s, 1H), 7.64 (d, J=8.3, 0.3H), 7.19 (d, J=8.8, 0.7H), 4.44 (dd, J=8.1, 4.6, 0.3H), 4.23 (dd, J=8.7, 4.4, 0.7H), 3.56/3.53 (two singlets, 3H), 3.48-3.40 (m, 2H), 2.22-2.10 (m, 1H), 0.85 (s, 9H), ˜0.84 (d, 0.9H, overlapped with t-Bu signal), 0.79 (d, J=7, 2.1H), 0.02/0.01/0.00 (three overlapping singlets, 6H). LC/MS: Anal. Calcd. for [M+Na]⁺ C₁₃H₂₇NNaO₅Si: 328.16. found 328.46. Cap-80b: NMR (CDCl₃, δ=7.24 ppm, 400 MHz), 6.00 (br d, J=6.8, 1H), 4.36 (dd, J=7.1, 3.1, 1H), 3.87 (dd, J=10.5, 3.0, 1H), 3.67 (s, 3H), 3.58 (dd, J=10.6, 4.8, 1H), 2.35 (m, 1H), 1.03 (d, J=7.1, 3H), 0.90 (s, 9H), 0.08 (s, 6H). LC/MS: Anal. Calcd. for [M+Na]⁺C₁₃H₂₇NNaO₅Si: 328.16. found 328.53. The crude products were utilized without further purification.

Prepared according to the protocol described by Falb et al. Synthetic Communications 1993, 23, 2839.

Cap-82 to Cap-85

Cap-82 to Cap-85 were synthesized from appropriate starting materials according to the procedure described for Cap-51 or Cap-13. The samples exhibited similar spectral profiles as that of their enantiomers (i.e., Cap-4, Cap-13, Cap-51 and Cap-52, respectively).

To a mixture of O-methyl-L-threonine (3.0 g, 22.55 mmol), NaOH (0.902 g, 22.55 mmol) in H₂O (15 mL) was added ClCO₂Me (1.74 mL, 22.55 mmol) dropwise at 0° C. The mixture was allowed to stir for 12 h and acidified to pH 1 using 1N HCl. The aqueous phase was extracted with EtOAc and (2×250 mL) and 10% MeOH in CH₂Cl₂ (250 mL) and the combined organic phases were concentrated under in vacuo to afford a colorless oil (4.18 g, 97%) which was of sufficient purity for use in subsequent steps. ¹HNMR (400 MHz, CDCl₃) δ 4.19 (s, 1H), 3.92-3.97 (m, 1H), 3.66 (s, 3H), 1.17 (d, J=7.7 Hz, 3H). LCMS: Anal. Calcd. for C₇H₁₃NO₅: 191; found: 190 (M−H)⁻.

To a mixture of L-homoserine (2.0 g, 9.79 mmol), Na₂CO₃ (2.08 g, 19.59 mmol) in H₂O (15 mL) was added ClCO₂Me (0.76 mL, 9.79 mmol) dropwise at 0° C. The mixture was allowed to stir for 48 h and acidified to pH 1 using 1N HCl. The aqueous phase was extracted with EtOAc and (2×250 mL) and the combined organic phases were concentrated in vacuo to afford a colorless solid (0.719 g, 28%) which was of sufficient purity for use in subsequent steps. ¹HNMR (400 MHz, CDCl₃) δ 4.23 (dd, J=4.5, 9.1 Hz, 1H), 3.66 (s, 3H), 3.43-3.49 (m, 2H), 2.08-2.14 (m, 1H), 1.82-1.89 (m, 1H). LCMS: Anal. Calcd. for C₇H₁₃NO₅: 191. found: 192 (M+H)⁺.

A mixture of L-valine (1.0 g, 8.54 mmol), 3-bromopyridine (1.8 mL, 18.7 mmol), K₂CO₃ (2.45 g, 17.7 mmol) and CuI (169 mg, 0.887 mmol) in DMSO (10 mL) was heated at 100° C. for 12 h. The reaction mixture was cooled to rt, poured into H₂O (ca. 150 mL) and washed with EtOAc (×2). The organic layers were extracted with a small amount of H₂O and the combined aq phases were acidified to ca. pH 2 with 6N HCl. The volume was reduced to about one-third and 20 g of cation exchange resin (Strata) was added. The slurry was allowed to stand for 20 min and loaded onto a pad of cation exchange resin (Strata) (ca. 25 g). The pad was washed with H₂O (200 mL), MeOH (200 mL), and then NH₃ (3M in MeOH, 2×200 mL). The appropriate fractions was concentrated in vacuo and the residue (ca. 1.1 g) was dissolved in H₂O, frozen and lyophylized. The title compound was obtained as a foam (1.02 g, 62%). ¹HNMR (400 MHz, DMSO-d₆) δ 8.00 (s, br, 1H), 7.68-7.71 (m, 1H), 7.01 (s, br, 1H), 6.88 (d, J=7.5 Hz, 1H), 5.75 (s, br, 1H), 3.54 (s, 1H), 2.04-2.06 (m, 1H), 0.95 (d, J=6.0 Hz, 3H), 0.91 (d, J=6.6 Hz, 3H). LCMS: Anal. Calcd. for C₁₀H₁₄N₂O₂: 194. found: 195 (M+H)⁺.

A mixture of L-valine (1.0 g, 8.54 mmol), 5-bromopyrimidine (4.03 g, 17.0 mmol), K₂CO₃ (2.40 g, 17.4 mmol) and CuI (179 mg, 0.94 mmol) in DMSO (10 mL) was heated at 100° C. for 12 h. The reaction mixture was cooled to RT, poured into H₂O (ca. 150 mL) and washed with EtOAc (×2). The organic layers were extracted with a small amount of H₂O and the combined aq phases were acidified to ca. pH 2 with 6N HCl. The volume was reduced to about one-third and 20 g of cation exchange resin (Strata) was added. The slurry was allowed to stand for 20 min and loaded onto a pad of cation exchange resin (Strata) (ca. 25 g). The pad was washed with H₂O (200 mL), MeOH (200 mL), and then NH₃ (3M in MeOH, 2×200 mL). The appropriate fractions was concentrated in vacuo and the residue (ca. 1.1 g) was dissolved in H₂O, frozen and lyophylized. The title compound was obtained as a foam (1.02 g, 62%). ¹HNMR (400 MHz, CD₃OD) showed the mixture to contain valine and the purity could not be estimated. The material was used as is in subsequent reactions. LCMS: Anal. Calcd. for C₉H₁₃N₃O₂: 195. found: 196 (M+H)⁺.

Cap-90 was prepared according to the method described for the preparation of Cap-1. The crude material was used as is in subsequent steps. LCMS: Anal. Calcd. for C₁₁H₁₅NO₂: 193. found: 192 (M−H)⁻.

The following caps were prepared according to the method used for preparation of cap 51 unless noted otherwise:

Cap Structure LCMS Cap-91

LCMS: Anal. Calcd. for C₁₁H₁₃NO₄: 223; found: 222 (M − H)⁻. Cap-92

LCMS: Anal. Calcd. for C₁₁H₁₃NO₄: 223; found: 222 (M − H)⁻. Cap-93

LCMS: Anal. Calcd. for C₁₀H₁₂N₂O₄: 224; found: 225 (M + H)⁺. Cap-94

LCMS: Anal. Calcd. for C₈H₁₁N₃O₄: 213; found: 214 (M + H)⁺. Cap-95

LCMS: Anal. Calcd. for C₁₃H₁₇NO₄: 251; found: 250 (M − H)⁻. Cap-96

LCMS: Anal. Calcd. for C₁₂H₁₅NO₄: 237; found: 236 (M − H)⁻. Cap-97

LCMS: Anal. Calcd. for C₉H₁₅NO₄: 201; found: 200 (M − H)⁻. Cap-98

LCMS: Anal. Calcd. for C₉H₁₅NO₄: 201; found: 202 (M + H)⁺. Cap-99

¹HNMR (400 MHz, CD₃OD) δ 3.88-3.94 (m, 1H), 3.60, 3.61 (s, 3H), 2.80 (m, 1H), 2.20 (m 1H), 1.82-1.94 (m, 3H), 1.45- 1.71 (m, 2H). Cap-99a

¹HNMR (400 MHz, CD₃OD) δ 3.88-3.94 (m, 1H), 3.60, 3.61 (s, 3H), 2.80 (m, 1H), 2.20 (m 1H), 1.82-1.94 (m, 3H), 1.45- 1.71 (m, 2H). Cap-100

LCMS: Anal. Calcd. for C₁₂H₁₄NO₄F: 255; found: 256 (M + H)⁺. Cap-101

LCMS: Anal. Calcd. for C₁₁H₁₃NO₄: 223; found: 222 (M − H)⁻. Cap-102

LCMS: Anal. Calcd. for C₁₁H₁₃NO₄: 223; found: 222 (M − H)⁻ Cap-103

LCMS: Anal. Calcd. for C₁₀H₁₂N₂O₄: 224; found: 225 (M + H)⁺. Cap-104

¹HNMR (400 MHz, CD₃OD) δ 3.60 (s, 3H), 3.50-3.53 (m, 1H), 2.66- 2.69 and 2.44-2.49 (m, 1H), 1.91-2.01 (m, 2H), 1.62-1.74 (m, 4H), 1.51- 1.62 (m, 2H). Cap-105

¹HNMR (400 MHz, CD₃OD) δ 3.60 (s, 3H), 3.33-3.35 (m, 1H, partially obscured by solvent), 2.37-2.41 and 2.16-2.23 (m, 1H), 1.94- 2.01 (m, 4H), 1.43- 1.53 (m, 2H), 1.17-1.29 (m, 2H). Cap-106

¹HNMR (400 MHz, CD₃OD) δ 3.16 (q, J = 7.3 Hz, 4H), 2.38-2.41 (m, 1H), 2.28-2.31 (m, 2H), 1.79-1.89 (m, 2H), 1.74 (app, ddd J = 3.5, 12.5, 15.9 Hz, 2H), 1.46 (app dt J = 4.0, 12.9 Hz, 2H), 1.26 (t, J = 7.3 Hz, 6H) Cap-107

LCMS: Anal. Calcd. for C₈H₁₀N₂O₄S: 230; found: 231 (M + H)⁺. Cap-108

LCMS: Anal. Calcd. for C₁₅H₁₇N₃O₄: 303; found: 304 (M + H)⁺. Cap-109

LCMS: Anal. Calcd. for C₁₀H₁₂N₂O₄: 224; found: 225 (M + H)⁺. Cap-110

LCMS: Anal. Calcd. for C₁₀H₁₂N₂O₄: 224; found: 225 (M + H)⁺. Cap-111

LCMS: Anal. Calcd. for C₁₂H₁₆NO₈P: 333; found: 334 (M + H)⁺. Cap-112

LCMS: Anal. Calcd. for C₁₃H₁₄N₂O₄: 262; found: 263 (M + H)⁺. Cap-113

LCMS: Anal. Calcd. for C₁₈H₁₉NO₅: 329; found: 330 (M + H)⁺. Cap-114

¹HNMR (400 MHz, CDCl₃) δ 4.82-4.84 (m, 1H), 4.00-4.05 (m, 2H), 3.77 (s, 3H), 2.56 (s, br, 2H) Cap-115

¹HNMR (400 MHz, CDCl₃) δ 5.13 (s, br, 1H), 4.13 (s, br, 1H), 3.69 (s, 3H), 2.61 (d, J = 5.0 Hz, 2H), 1.28 (d, J = 9.1 Hz, 3H). Cap-116

¹HNMR (400 MHz, CDCl₃) δ 5.10 (d, J = 8.6 Hz, 1H), 3.74-3.83 (m, 1H), 3.69 (s, 3H), 2.54- 2.61 (m, 2H), 1.88 (sept, J = 7.0 Hz, 1H), 0.95 (d, J = 7.0 Hz, 6H).

Cap-117 to Cap-123

For the preparation of Cap-117 to Cap-123 the Boc amino acids were obtained from commercially sources and were deprotected by treatment with 25% TFA in CH₂Cl₂. After complete reaction as judged by LCMS the solvents were removed in vacuo and the corresponding TFA salt of the amino acid was carbamoylated with methyl chloroformate according to the procedure described for Cap-51.

Cap Structure LCMS Cap-117

LCMS: Anal. Calcd. for C₁₂H₁₅NO₄: 237; found: 238 (M + H)⁺. Cap-118

LCMS: Anal. Calcd. for C₁₀H₁₃NO₄S: 243; found: 244 (M + H)⁺. Cap-119

LCMS: Anal. Calcd. for C₁₀H₁₃NO₄S: 243; found: 244 (M + H)⁺. Cap-120

LCMS: Anal. Calcd. for C₁₀H₁₃NO₄S: 243; found: 244 (M + H)⁺. Cap-121

¹HNMR (400 MHz, CDCl₃) δ 4.06-4.16 (m, 1H), 3.63 (s, 3H), 3.43 (s, 1H), 2.82 and 2.66 (s, br, 1H), 1.86- 2.10 (m, 3H), 1.64- 1.76 (m, 2H), 1.44- 1.53 (m, 1H). Cap-122

¹HNMR profile is similar to that of its enantiomer, Cap-121. Cap-123

LCMS: Anal. Calcd. for C₂₇H₂₆N₂O₆: 474; found: 475 (M + H)⁺.

The hydrochloride salt of L-threonine tert-butyl ester was carbamoylated according to the procedure for Cap-51. The crude reaction mixture was acidified with 1N HCl to pH˜1 and the mixture was extracted with EtOAc (2×50 mL). The combined organic phases were concentrated in vacuo to give a colorless oil which solidified on standing. The aqueous layer was concentrated in vacuo and the resulting mixture of product and inorganic salts was triturated with EtOAc-CH₂Cl₂-MeOH (1:1:0.1) and then the organic phase concentrated in vacuo to give a colorless oil which was shown by LCMS to be the desired product. Both crops were combined to give 0.52 g of a solid. ¹HNMR (400 MHz, CD₃OD) δ 4.60 (m, 1H), 4.04 (d, J=5.0 Hz, 1H), 1.49 (d, J=6.3 Hz, 3H). LCMS: Anal. Calcd. for C₅H₇NO₄: 145. found: 146 (M+H)⁺.

To a suspension of Pd(OH)₂, (20%, 100 mg), aqueous formaldehyde (37% wt, 4 ml), acetic acid, (0.5 mL) in methanol (15 mL) was added (S)-4-amino-2-(tert-butoxycarbonylamino)butanoic acid (1 g, 4.48 mmol). The reaction was purged several times with hydrogen and was stirred overnight with an hydrogen balloon room temp. The reaction mixture was filtered through a pad of diatomaceous earth (Celite®), and the volatile component was removed in vacuo. The resulting crude material was used as is for the next step. LC/MS: Anal. Calcd. for C₁₁H₂₂N₂O₄: 246. found: 247 (M+H)⁺.

This procedure is a modification of that used to prepare Cap-51. To a suspension of 3-methyl-L-histidine (0.80 g, 4.70 mmol) in THF (10 mL) and H₂O (10 mL) at 0° C. was added NaHCO₃ (0.88 g, 10.5 mmol). The resulting mixture was treated with ClCO₂Me (0.40 mL, 5.20 mmol) and the mixture allowed to stir at 0° C. After stirring for ca. 2 h LCMS showed no starting material remaining. The reaction was acidified to pH 2 with 6 N HCl.

The solvents were removed in vacuo and the residue was suspended in 20 mL of 20% MeOH in CH₂Cl₂. The mixture was filtered and concentrated to give a light yellow foam (1.21 g). LCMS and ¹H NMR showed the material to be a 9:1 mixture of the methyl ester and the desired product. This material was taken up in THF (10 mL) and H₂O (10 mL), cooled to 0° C. and LiOH (249.1 mg, 10.4 mmol) was added. After stirring ca. 1 h LCMS showed no ester remaining. Therefore the mixture was acidified with 6N HCl and the solvents removed in vacuo. LCMS and ¹H NMR confirm the absence of the ester. The title compound was obtained as its HCl salt contaminated with inorganic salts (1.91 g, >100%). The compound was used as is in subsequent steps without further purification. ¹HNMR (400 MHz, CD₃OD) δ 8.84, (s, 1H), 7.35 (s, 1H), 4.52 (dd, J=5.0, 9.1 Hz, 1H), 3.89 (s, 3H), 3.62 (s, 3H), 3.35 (dd, J=4.5, 15.6 Hz, 1H, partially obscured by solvent), 3.12 (dd, J=9.0, 15.6 Hz, 1H). LCMS: Anal. Calcd. for C₉H₁₃N₃O₄: 227.09. found: 228.09 (M+H)⁺.

Cap-127 was prepared according to the method for Cap-126 above starting from (S)-2-amino-3-(1-methyl-1H-imidazol-4-yl)propanoic acid (1.11 g, 6.56 mmol), NaHCO₃ (1.21 g, 14.4 mmol) and ClCO₂Me (0.56 mL, 7.28 mmol). The title compound was obtained as its HCl salt (1.79 g, >100%) contaminated with inorganic salts. LCMS and ¹H NMR showed the presence of ca. 5% of the methyl ester. The crude mixture was used as is without further purification. ¹HNMR (400 MHz, CD₃OD) δ 8.90 (s, 1H), 7.35 (s, 1H), 4.48 (dd, J=5.0, 8.6 Hz, 1H), 3.89 (s, 3H), 3.62 (s, 3H), 3.35 (m, 1H), 3.08 (m, 1H); LCMS: Anal. Calcd. for C₉H₁₃N₃O₄: 227.09. found: 228 (M+H)⁺.

Preparation of Cap-128

Step 1. Preparation of (S)-benzyl 2-(tert-butoxycarbonylamino)pent-4-ynoate (cj-27b)

To a solution of cj-27a (1.01 g, 4.74 mmol), DMAP (58 mg, 0.475 mmol) and iPr₂NEt (1.7 mL, 9.8 mmol) in CH₂Cl₂ (100 mL) at 0° C. was added Cbz-Cl (0.68 mL, 4.83 mmol). The solution was allowed to stir for 4 h at 0° C., washed (1N KHSO₄, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo. The residue was purified by flash column chromatography (TLC 6:1 hex:EtOAc) to give the title compound (1.30 g, 91%) as a colorless oil. ¹HNMR (400 MHz, CDCl₃) δ 7.35 (s, 5H), 5.35 (d, br, J=8.1 Hz, 1H), 5.23 (d, J=12.2 Hz, 1H), 5.17 (d, J=12.2 Hz, 1H), 4.48-4.53 (m, 1H), 2.68-2.81 (m, 2H), 2.00 (t, J=2.5 Hz, 1H), 1.44 (s, 9H). LCMS: Anal. Calcd. for C₁₇H₂₁NO₄: 303. found: 304 (M+H)⁺.

Step 2. Preparation of (S)-benzyl 3-(1-benzyl-1H-1,2,3-triazol-4-yl)-2-(tert-butoxycarbonylamino)propanoate (cj-28)

To a mixture of (S)-benzyl 2-(tert-butoxycarbonylamino)pent-4-ynoate (0.50 g, 1.65 mmol), sodium ascorbate (0.036 g, 0.18 mmol), CuSO₄-5H₂O (0.022 g, 0.09 mmol) and NaN₃ (0.13 g, 2.1 mmol) in DMF-H₂O (5 mL, 4:1) at rt was added BnBr (0.24 mL, 2.02 mmol) and the mixture was warmed to 65° C. After 5 h LCMS indicated low conversion. A further portion of NaN₃ (100 mg) was added and heating was continued for 12 h. The reaction was poured into EtOAc and H₂O and shaken. The layers were separated and the aqueous layer extracted 3× with EtOAc and the combined organic phases washed (H₂O ×3, brine), dried (Na₂SO₄), filtered, and concentrated. The residue was purified by flash (Biotage, 40+M 0-5% MeOH in CH₂Cl₂; TLC 3% MeOH in CH₂Cl₂) to afford a light yellow oil which solidified on standing (748.3 mg, 104%). The NMR was consistent with the desired product but suggests the presence of DMF. The material was used as is without further purification. ¹HNMR (400 MHz, DMSO-d₆) δ 7.84 (s, 1H), 7.27-7.32 (m, 10H), 5.54 (s, 2H), 5.07 (s, 2H), 4.25 (m, 1H), 3.16 (dd, J=1.0, 5.3 Hz, 1H), 3.06 (dd, J=5.3, 14.7 Hz), 2.96 (dd, J=9.1, 14.7 Hz, 1H), 1.31 (s, 9H). LCMS: Anal. Calcd. for C₂₄H₂₈N₄O₄: 436. found: 437 (M+H)⁺.

Step 3. Preparation of (S)-benzyl 3-(1-benzyl-1H-1,2,3-triazol-4-yl)-2-(methoxycarbonylamino)propanoate (cj-29)

A solution of (S)-benzyl 3-(1-benzyl-1H-1,2,3-triazol-4-yl)-2-(tert-butoxycarbonylamino)propanoate (0.52 g, 1.15 mmol) in CH₂Cl₂ was added TFA (4 mL). The mixture was allowed to stir at room temperature for 2 h. The mixture was concentrated in vacuo to give a colorless oil which solidified on standing. This material was dissolved in THF-H₂O and cooled to 0° C. Solid NaHCO₃ (0.25 g, 3.00 mmol) was added followed by ClCO₂Me (0.25 mL, 3.25 mmol). After stirring for 1.5 h the mixture was acidified to pH˜2 with 6N HCl and then poured into H₂O-EtOAc. The layers were separated and the aq phase extracted 2× with EtOAc. The combined org layers were washed (H₂O, brine), dried (Na₂SO₄), filtered, and concentrated in vacuo to give a colorless oil (505.8 mg, 111%, NMR suggested the presence of an unidentified impurity) which solidified while standing on the pump. The material was used as is without further purification. ¹HNMR (400 MHz, DMSO-d₆) δ 7.87 (s, 1H), 7.70 (d, J=8.1 Hz, 1H), 7.27-7.32 (m, 10H), 5.54 (s, 2H), 5.10 (d, J=12.7 Hz, 1H), 5.06 (d, J=12.7 Hz, 1H), 4.32-4.37 (m, 1H), 3.49 (s, 3H), 3.09 (dd, J=5.6, 14.7 Hz, 1H), 2.98 (dd, J=9.6, 14.7 Hz, 1H). LCMS: Anal. Calcd. for C₂₁H₂₂N₄O₄: 394. found: 395 (M+H)⁺.

Step 4. Preparation of (S)-2-(methoxycarbonylamino)-3-(1H-1,2,3-triazol-4-yl)propanoic acid (Cap-128)

(S)-benzyl 3-(1-benzyl-1H-1,2,3-triazol-4-yl)-2-(methoxycarbonylamino)propanoate (502 mg, 1.11 mmol) was hydrogenated in the presence of Pd—C (82 mg) in MeOH (5 mL) at atmospheric pressure for 12 h. The mixture was filtered through diatomaceous earth (Celite®) and concentrated in vacuo. (S)-2-(methoxycarbonylamino)-3-(1H-1,2,3-triazol-4-yl)propanoic acid was obtained as a colorless gum (266 mg, 111%) which was contaminated with ca. 10% of the methyl ester. The material was used as is without further purification. ¹HNMR (400 MHz, DMSO-d₆) δ 12.78 (s, br, 1H), 7.59 (s, 1H), 7.50 (d, J=8.0 Hz, 1H), 4.19-4.24 (m, 1H), 3.49 (s, 3H), 3.12 (dd, J=4.8 Hz, 14.9 Hz, 1H), 2.96 (dd, J=9.9, 15.0 Hz, 1H). LCMS: Anal. Calcd. for C₂H₁₀N₄O₄: 214. found: 215 (M+H)⁺.

Preparation of Cap-129

Step 1. Preparation of (S)-2-(benzyloxycarbonylamino)-3-(1H-pyrazol-1-yl)propanoic acid (cj-31)

A suspension of (S)-benzyl 2-oxooxetan-3-ylcarbamate (0.67 g, 3.03 mmol), and pyrazole (0.22 g, 3.29 mmol) in CH₃CN (12 mL) was heated at 50° C. for 24 h. The mixture was cooled to rt overnight and the solid filtered to afford (S)-2-(benzyloxycarbonylamino)-3-(1H-pyrazol-1-yl)propanoic acid (330.1 mg). The filtrate was concentrated in vacuo and then triturated with a small amount of CH₃CN (ca. 4 mL) to afford a second crop (43.5 mg). Total yield 370.4 mg (44%). m.p. 165.5-168° C. lit m.p. 168.5-169.5 [Vederas et al. J. Am. Chem. Soc. 1985, 107, 7105]. ¹HNMR (400 MHz, CD₃OD) δ 7.51 (d, J=2.0, 1H), 7.48 (s, J=1.5 Hz, 1H), 7.24-7.34 (m, 5H), 6.23 m, 1H), 5.05 (d, 12.7H, 1H), 5.03 (d, J=12.7 Hz, 1H), 4.59-4.66 (m, 2H), 4.42-4.49 (m, 1H). LCMS: Anal. Calcd. for C₁₄H₁₅N₃O₄: 289. found: 290 (M+H)⁺.

Step 2. Preparation of (S)-2-(methoxycarbonylamino)-3-(1H-pyrazol-1-yl)propanoic acid (Cap-129)

(S)-2-(benzyloxycarbonylamino)-3-(1H-pyrazol-1-yl)propanoic acid (0.20 g, 0.70 mmol) was hydrogenated in the presence of Pd—C (45 mg) in MeOH (5 mL) at atmospheric pressure for 2 h. The product appeared to be insoluble in MeOH, therefore the reaction mixture was diluted with 5 mL H₂O and a few drops of 6N HCl. The homogeneous solution was filtered through diatomaceous earth (Celite®), and the MeOH removed in vacuo. The remaining solution was frozen and lyophylized to give a yellow foam (188.9 mg). This material was suspended in THF-H₂O (1:1, 10 mL) and then cooled to 0° C. To the cold mixture was added NaHCO₃ (146.0 mg, 1.74 mmol) carefully (evolution of CO₂). After gas evolution had ceased (ca. 15 min) ClCO₂Me (0.06 mL, 0.78 mmol) was added dropwise. The mixture was allowed to stir for 2 h and was acidified to pH˜2 with 6N HCl and poured into EtOAc. The layers were separated and the aqueous phase extracted with EtOAC (×5). The combined organic layers were washed (brine), dried (Na₂SO₄), filtered, and concentrated to give the title compound as a colorless solid (117.8 mg, 79%). ¹HNMR (400 MHz, DMSO-d₆) δ 13.04 (s, 1H), 7.63 (d, J=2.6 Hz, 1H), 7.48 (d, J=8.1 Hz, 1H), 7.44 (d, J=1.5 Hz, 1H), 6.19 (app t, J=2.0 Hz, 1H), 4.47 (dd, J=3.0, 12.9 Hz, 1H), 4.29-4.41 (m, 2H), 3.48 (s, 3H). LCMS: Anal. Calcd. for C₈H₁₁N₃O₄: 213. found: 214 (M+H)⁺.

Cap-130 was prepared by acylation of commercially available (R)-phenylglycine analogous to the procedure given in: Calmes, M.; Daunis, J.; Jacquier, R.; Verducci, J. Tetrahedron, 1987, 43(10), 2285.

Step a: Dimethylcarbamoyl chloride (0.92 mL, 10 mmol) was added slowly to a solution of (S)-benzyl 2-amino-3-methylbutanoate hydrochloride (2.44 g; 10 mmol) and Hunig's base (3.67 mL, 21 mmol) in THF (50 mL). The resulting white suspension was stirred at room temperature overnight (16 hours) and concentrated under reduced pressure. The residue was partitioned between ethyl acetate and water. The organic layer was washed with brine, dried (MgSO₄), filtered, and concentrated under reduced pressure. The resulting yellow oil was purified by flash chromatography, eluting with ethyl acetate:hexanes (1:1). Collected fractions were concentrated under vacuum providing 2.35 g (85%) of clear oil. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 0.84 (d, J=6.95 Hz, 3H), 0.89 (d, J=6.59 Hz, 3H), 1.98-2.15 (m, 1H), 2.80 (s, 6H), 5.01-5.09 (m, J=12.44 Hz, 1H), 5.13 (d, J=12.44 Hz, 1H), 6.22 (d, J=8.05 Hz, 1H), 7.26-7.42 (m, 5H). LC (Cond. 1): RT=1.76 min; MS: Anal. Calcd. for [M+H]⁺C₁₆H₂₂N₂O₃: 279.17. found 279.03.

Step b: To a MeOH (50 mL) solution of the intermediate prepared above (2.35 g; 8.45 mmol) was added Pd/C (10%; 200 mg) and the resulting black suspension was flushed with N₂ (3×) and placed under 1 atm of H₂. The mixture was stirred at room temperature overnight and filtered though a microfiber filter to remove the catalyst. The resulting clear solution was then concentrated under reduced pressure to obtain 1.43 g (89%) of Cap-131 as a white foam, which was used without further purification. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 0.87 (d, J=4.27 Hz, 3H), 0.88 (d, J=3.97 Hz, 3H), 1.93-2.11 (m, 1H), 2.80 (s, 6H), 3.90 (dd, J=8.39, 6.87 Hz, 1H), 5.93 (d, J=8.54 Hz, 1H), 12.36 (s, 1H). LC (Cond. 1): RT=0.33 min; MS: Anal. Calcd. for [M+H]⁺C₈H₁₇N₂O₃: 189.12. found 189.04.

Cap-132 was prepared from (S)-benzyl 2-aminopropanoate hydrochloride according to the method described for Cap-131. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 1.27 (d, J=7.32 Hz, 3H), 2.80 (s, 6H), 4.06 (qt, 1H), 6.36 (d, J=7.32 Hz, 1H), 12.27 (s, 1H). LC (Cond. 1): RT=0.15 min; MS: Anal. Calcd. for [M+H]⁺ C₆H₁₃N₂O₃: 161.09. found 161.00.

Cap-133 was prepared from (S)-tert-butyl 2-amino-3-methylbutanoate hydrochloride and 2-fluoroethyl chloroformate according to the method described for Cap-47. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 0.87 (t, J=6.71 Hz, 6H), 1.97-2.10 (m, 1H), 3.83 (dd, J=8.39, 5.95 Hz, 1H), 4.14-4.18 (m, 1H), 4.20-4.25 (m, 1H), 4.50-4.54 (m, 1H), 4.59-4.65 (m, 1H), 7.51 (d, J=8.54 Hz, 1H), 12.54 (s, 1H).

Cap-134 was prepared from (S)-diethyl alanine and methyl chloroformate according to the method described for Cap-51. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 0.72-0.89 (m, 6H), 1.15-1.38 (m, 4H), 1.54-1.66 (m, 1H), 3.46-3.63 (m, 3H), 4.09 (dd, J=8.85, 5.19 Hz, 1H), 7.24 (d, J=8.85 Hz, 1H), 12.55 (s, 1H). LC (Cond. 2): RT=0.66 min; LC/MS: Anal. Calcd. for [M+H]⁺ C₉H₁₈NO₄: 204.12. found 204.02.

A solution of D-2-amino-(4-fluorophenyl)acetic acid (338 mg, 2.00 mmol), 1N HCl in diethylether (2.0 mL, 2.0 mmol) and formalin (37%, 1 mL) in methanol (5 mL) was subjected to balloon hydrogenation over 10% palladium on carbon (60 mg) for 16 h at 25° C. The mixture was then filtered through Celite to afford the HCl salt of Cap-135 as a white foam (316 mg, 80%). ¹H NMR (300 MHz, MeOH-d₄) δ 7.59 (dd, J=8.80, 5.10 Hz, 2H), 7.29 (t, J=8.6 Hz, 2H), 5.17 (s, 1H), 3.05 (v br s, 3H), 2.63 (v br s, 3H); R_(t)=0.19 min (Cond.-MS-W5); 95% homogeneity index; LRMS: Anal. Calcd. for [M+H]⁺ C₁₀H₁₃FNO₂: 198.09. found: 198.10.

To a cooled (−50° C.) suspension of 1-benzyl-1H-imidazole (1.58 g, 10.0 mmol) in anhydrous diethyl ether (50 mL) under nitrogen was added n-butyl lithium (2.5 M in hexanes, 4.0 mL, 10.0 mmol) dropwise. After being stirred for 20 min at −50° C., dry carbon dioxide (passed through Drierite) was bubbled into the reaction mixture for 10 min before it was allowed to warm up to 25° C. The heavy precipitate which formed on addition of carbon dioxide to the reaction mixture was filtered to yield a hygroscopic, white solid which was taken up in water (7 mL), acidified to pH=3, cooled, and induced to crystallize with scratching. Filtration of this precipitate gave a white solid which was suspended in methanol, treated with 1N HCl/diethyl ether (4 mL) and concentrated in vacuo. Lyophilization of the residue from water (5 mL) afforded the HCl salt of Cap-136 as a white solid (817 mg, 40%). ¹H NMR (300 MHz, DMSO-d₆) δ 7.94 (d, J=1.5 Hz, 1H), 7.71 (d, J=1.5 Hz, 1H), 7.50-7.31 (m, 5H), 5.77 (s, 2H); R₄=0.51 min (Cond.-MS-W5); 95% homogeneity index; LRMS: Anal. Calc. for [M+H]⁺ C₁₁H₁₂N₂O₂: 203.08. found: 203.11.

A suspension of 1-chloro-3-cyanoisoquinoline (188 mg, 1.00 mmol; prepared according to the procedure in WO 2003/099274) (188 mg, 1.00 mmol), cesium fluoride (303.8 mg, 2.00 mmol), bis(tri-tert-butylphosphine)palladium dichloride (10 mg, 0.02 mmol) and 2-(tributylstannyl)furan (378 μL, 1.20 mmol) in anhydrous dioxane (10 mL) under nitrogen was heated at 80° C. for 16 h before it was cooled to 25° C. and treated with saturated, aqueous potassium fluoride solution with vigorous stirring for 1 h. The mixture was partitioned between ethyl acetate and water and the organic phase was separated, washed with brine, dried over Na₂SO₄, filtered and concentrated. Purification of the residue on silica gel (elution with 0% to 30% ethyl acetate/hexanes) afforded Cap-137, step a (230 mg, 105%) as a white solid which was carried forward directly. R_(t)=1.95 min (Cond.-MS-W2); 90% homogeneity index; LRMS: Anal. Calc. for [M+H]⁺C₁₄H₈N₂O: 221.07. found: 221.12.

Cap-137

To a suspension of Cap 137, step a, (110 mg, 0.50 mmol) and sodium periodate (438 mg, 2.05 mmol) in carbon tetrachloride (1 mL), acetonitrile (1 mL) and water (1.5 mL) was added ruthenium trichloride hydrate (2 mg, 0.011 mmol). The mixture was stirred at 25° C. for 2 h and then partitioned between dichloromethane and water. The aqueous layer was separated, extracted twice more with dichloromethane and the combined dichloromethane extracts were dried over Na₂SO₄, filtered and concentrated. Trituration of the residue with hexanes afforded Cap-137 (55 mg, 55%) as a grayish-colored solid. R_(t)=1.10 min (Cond.-MS-W2); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₁H₈N₂O₂: 200.08. found: 200.08.

Caps 138 to 158

Synthetic Strategy. Method A.

To a stirred suspension of 5-hydroxyisoquinoline (prepared according to the procedure in WO 2003/099274) (2.0 g, 13.8 mmol) and triphenylphosphine (4.3 g, 16.5 mmol) in dry tetrahydrofuran (20 mL) was added dry methanol (0.8 mL) and diethyl azodicarboxylate (3.0 mL, 16.5 mmol) portionwise. The mixture was stirred at room temperature for 20 h before it was diluted with ethyl acetate and washed with brine, dried over Na₂SO₄, filtered and concentrated. The residue was preabsorbed onto silica gel and chromatographed (elution with 40% ethyl acetate/hexanes) to afford Cap-138, step a (1.00 g, 45%) as a light yellow solid. ¹H NMR (CDCl₃, 500 MHz) δ 9.19 (s, 1H), 8.51 (d, J=6.0 Hz, 1H), 7.99 (d, J=6.0 Hz, 1H), 7.52-7.50 (m, 2H), 7.00-6.99 (m, 1H), 4.01 (s, 3H); R_(t)=0.66 min (Cond.-D2); 95% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺ C₁₀H₁₀NO: 160.08. found 160.1.

To a stirred solution of Cap 138, step a (2.34 g, 14.7 mmol) in anhydrous dichloromethane (50 mL) at room temperature was added meta-chloroperbenzoic acid (77%, 3.42 g, 19.8 mmol) in one portion. After being stirred for 20 h, powdered potassium carbonate (2.0 g) was added and the mixture was stirred for 1 h at room temperature before it was filtered and concentrated in vacuo to afford Cap-138, step b (2.15 g, 83%) as a pale, yellow solid which was sufficiently pure to carry forward directly. ¹H NMR (CDCl₃, 400 MHz) δ 8.73 (d, J=1.5 Hz, 1H), 8.11 (dd, J=7.3, 1.7 Hz, 1H), 8.04 (d, J=7.1 Hz, 1H), 7.52 (t, J=8.1 Hz, 1H), 7.28 (d, J=8.3 Hz, 1H), 6.91 (d, J=7.8 Hz, 1H), 4.00 (s, 3H); R_(t)=0.92 min, (Cond.-D1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₀H₁₀NO₂: 176.07. found: 176.0.

To a stirred solution of Cap 138, step b (0.70 g, 4.00 mmol) and triethylamine (1.1 mL, 8.00 mmol) in dry acetonitrile (20 mL) at room temperature under nitrogen was added trimethylsilylcyanide (1.60 mL, 12.00 mmol). The mixture was heated at 75° C. for 20 h before it was cooled to room temperature, diluted with ethyl acetate and washed with saturated sodium bicarbonate solution and brine prior to drying over Na₂SO₄ and solvent concentration. The residue was flash chromatographed on silica gel (gradient elution with 5% ethyl acetate in hexanes to 25% ethyl acetate in hexanes) to afford Cap-138, step c (498.7 mg, 68%) as a white, crystalline solid along with 223 mg (30%) of additional Cap-138, step c recovered from the filtrate. ¹H NMR (CDCl₃, 500 MHz) δ 8.63 (d, J=5.5 Hz, 1H), 8.26 (d, J=5.5 Hz, 1H), 7.88 (d, J=8.5 Hz, 1H), 7.69 (t, J=8.0 Hz, 1H), 7.08 (d, J=7.5 Hz, 1H), 4.04 (s, 3H); R_(t)=1.75 min, (Cond.-D1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₁H₉N₂O: 185.07. found: 185.10.

Cap-138

Cap-138, step c (0.45 g, 2.44 mmol) was treated with 5N sodium hydroxide solution (10 mL) and the resulting suspension was heated at 85° C. for 4 h, cooled to 25° C., diluted with dichloromethane and acidified with 1N hydrochloric acid. The organic phase was separated, washed with brine, dried over Na₂SO₄, concentrated to ¼ volume and filtered to afford Cap-138 (0.44 g, 88.9%) as a yellow solid. ¹H NMR (DMSO-d₅, 400 MHz) δ 13.6 (br s, 1H), 8.56 (d, J=6.0 Hz, 1H), 8.16 (d, J=6.0 Hz, 1H), 8.06 (d, J=8.8 Hz, 1H), 7.71-7.67 (m, 1H), 7.30 (d, J=8.0 Hz, 1H), 4.02 (s, 3H); R_(t)=0.70 min (Cond.-D1); 95% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₁H₁₀NO₃: 204.07. found: 204.05.

Synthetic Strategy. Method B (Derived from Tetrahedron Letters, 2001, 42, 6707).

To a thick-walled, screw-top vial containing an argon-degassed suspension of 1-chloro-6-methoxyisoquinoline (1.2 g, 6.2 mmol; prepared according to the procedure in WO 2003/099274), potassium cyanide (0.40 g, 6.2 mmol), 1,5-bis(diphenylphosphino)pentane (0.27 g, 0.62 mmol) and palladium (II) acetate (70 mg, 0.31 mmol) in anhydrous toluene (6 mL) was added N,N,N′,N′-tetramethylethylenediamine (0.29 mL, 2.48 mmol). The vial was sealed, heated at 150° C. for 22 h and then allowed to cool to 25° C. The reaction mixture was diluted with ethyl acetate, washed with water and brine, dried over Na₂SO₄, filtered and concentrated. The residue was purified on silica gel (gradient elution with 5% ethyl acetate/hexanes to 25% ethyl acetate/hexanes) to afford Cap-139, step a (669.7 mg, 59%) as a white solid. ¹H NMR (CDCl₃, 500 MHz) δ 8.54 (d, J=6.0 Hz, 1H), 8.22 (d, J=9.0 Hz, 1H), 7.76 (d, J=5.5 Hz, 1H), 7.41-7.39 (m, 1H), 7.13 (d, J=2.0 Hz, 1H), 3.98 (s, 3H); R_(t)=1.66 min (Cond.-D1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₁H₉N₂O: 185.07. found: 185.2.

Cap-139

Cap-139 was prepared from the basic hydrolysis of Cap-139, step a with 5N NaOH according to the procedure described for Cap 138. ¹H NMR (400 MHz, DMSO-d₆) δ 13.63 (v br s, 1H), 8.60 (d, J=9.3 Hz, 1H), 8.45 (d, J=5.6 Hz, 1H), 7.95 (d, J=5.9 Hz, 1H), 7.49 (d, J=2.2 Hz, 1H), 7.44 (dd, J=9.3, 2.5 Hz, 1H), 3.95 (s, 3H); R_(t)=0.64 min (Cond.-D1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₁H₁₀NO₃: 204.07. found: 204.05.

To a vigorously-stirred mixture of 1,3-dichloro-5-ethoxyisoquinoline (482 mg, 2.00 mmol; prepared according to the procedure in WO 2005/051410), palladium (II) acetate (9 mg, 0.04 mmol), sodium carbonate (223 mg, 2.10 mmol) and 1,5-bis(diphenylphosphino)pentane (35 mg, 0.08 mmol) in dry dimethylacetamide (2 mL) at 25° C. under nitrogen was added N,N,N′,N′-tetramethylethylenediamine (60 mL, 0.40 mmol). After 10 min, the mixture was heated to 150° C., and then a stock solution of acetone cyanohydrin (prepared from 4574 of acetone cyanohydrin in 4.34 mL DMA) was added in 1 mL portions over 18 h using a syringe pump. The mixture was then partitioned between ethyl acetate and water and the organic layer was separated, washed with brine, dried over Na₂SO₄, filtered and concentrated. The residue was purified on silica gel (gradient elution with 10% ethyl acetate in hexanes to 40% ethyl acetate in hexanes) to afford Cap-140, step a (160 mg, 34%) as a yellow solid. R_(t)=2.46 min (Cond.-MS-W2); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₂H₉ClN₂O: 233.05. found: 233.08.

Cap-140

Cap-140 was prepared by the acid hydrolysis of Cap-140, step a with 12N HCl as described in the procedure for the preparation of Cap 141, described below. R_(t)=2.24 min (Cond.-MS-W2); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₂H₁₁ClNO₃: 252.04. found: 252.02.

Cap-141, step a was prepared from 1-bromo-3-fluoroisoquinoline (prepared from 3-amino-1-bromoisoquinoline using the procedure outlined in J. Med. Chem. 1970, 13, 613) as described in the procedure for the preparation of Cap-140, step a (vide supra). ¹H NMR (500 MHz, CDCl₃) δ 8.35 (d, J=8.5 Hz, 1H), 7.93 (d, J=8.5 Hz, 1H), 7.83 (t, J=7.63 Hz, 1H), 7.77-7.73 (m, 1H), 7.55 (s, 1H); R_(t)=1.60 min (Cond.-D1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₀H₆FN₂: 173.05. found: 172.99.

Cap-141

Cap-141, step a (83 mg, 0.48 mmol) was treated with 12N HCl (3 mL) and the resulting slurry was heated at 80° C. for 16 h before it was cooled to room temperature and diluted with water (3 mL). The mixture was stirred for 10 min and then filtered to afford Cap-141 (44.1 mg, 48%) as an off-white solid. The filtrate was diluted with dichloromethane and washed with brine, dried over Na₂SO₄, and concentrated to afford additional Cap-141 (29.30 mg, 32%) which was sufficiently pure to be carried forward directly. ¹H NMR (DMSO-d₆, 500 MHz) δ 14.0 (br s, 1H), 8.59-8.57 (m, 1H), 8.10 (d, J=8.5 Hz, 1H), 7.88-7.85 (m, 2H), 7.74-7.71 (m, 1H); R_(t)=1.33 min (Cond.-D1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺ C₁₀H₇FNO₂: 192.05. found: 191.97.

Cap-142, step a was prepared from 4-bromoisoquinoline N-oxide as described in the two-step procedure for the preparation of Cap-138, steps b and c. R_(t)=1.45 min (Cond.-MS-W1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺ C₁₀H₆BrN₂: 232.97. found: 233.00.

To an argon-degassed suspension of Cap-142, step a (116 mg, 0.50 mmol), potassium phosphate tribasic (170 mg, 0.80 mmol), palladium (II) acetate (3.4 mg, 0.015 mmol) and 2-(dicyclohexylphosphino)biphenyl (11 mg, 0.03 mmol) in anhydrous toluene (1 mL) was added morpholine (61 μL, 0.70 mmol). The mixture was heated at 100° C. for 16 h, cooled to 25° C., filtered through diatomaceous earth (Celite®) and concentrated. Purification of the residue on silica gel (gradient elution with 10% to 70% ethyl acetate in hexanes) afforded Cap-142, step b (38 mg, 32%) as a yellow solid which was carried forward directly. R_(t)=1.26 min (Cond.-MS-W1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₄H₁₄N₃O: 240.11. found: 240.13.

Cap-142

Cap-142 was prepared from Cap-142, step b with 5N sodium hydroxide as described in the procedure for Cap 138. R_(t)=0.72 min (Cond.-MS-W1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺ C₁₄H₁₅N₂O₃: 259.11. found: 259.08.

To a stirred solution of 3-amino-1-bromoisoquinoline (444 mg, 2.00 mmol) in anhydrous dimethylformamide (10 mL) was added sodium hydride (60%, unwashed, 96 mg, 2.4 mmol) in one portion. The mixture was stirred at 25° C. for 5 min before 2-bromoethyl ether (90%, 250 μL, 2.00 mmol) was added. This mixture was stirred further at 25° C. for 5 h and at 75° C. for 72 h before it was cooled to 25° C., quenched with saturated ammonium chloride solution and diluted with ethyl acetate. The organic layer was separated, washed with water and brine, dried over Na₂SO₄, filtered and concentrated. Purification of the residue on silica gel (gradient elution with 0% to 70% ethyl acetate in hexanes) afforded Cap-143, step a (180 mg, 31%) as a yellow solid. R₁=1.75 min (Cond.-MS-W1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺ C₁₃H₁₄BrN₂O: 293.03. found: 293.04.

Cap-143

To a cold (−60° C.) solution of Cap-143, step a (154 mg, 0.527 mmol) in anhydrous tetrahydrofuran (5 mL) was added a solution of n-butyllithium in hexanes (2.5 M, 0.25 mL, 0.633 mmol). After 10 min, dry carbon dioxide was bubbled into the reaction mixture for 10 min before it was quenched with 1N HCl and allowed to warm to 25° C. The mixture was then extracted with dichloromethane (3×30 mL) and the combined organic extracts were concentrated in vacuo. Purification of the residue by reverse phase HPLC (MeOH/water/TFA) afforded Cap-143 (16 mg, 12%). R_(t)=1.10 min (Cond.-MS-W1); 90% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₄H₁₅N₂O₃: 259.11. found: 259.08.

1,3-Dichloroisoquinoline (2.75 g, 13.89 mmol) was added in small portions to a cold (0° C.) solution of fuming nitric acid (10 mL) and concentrated sulfuric acid (10 mL). The mixture was stirred at 0° C. for 0.5 h before it was gradually warmed to 25° C. where it stirred for 16 h. The mixture was then poured into a beaker containing chopped ice and water and the resulting suspension was stirred for 1 h at 0° C. before it was filtered to afford Cap-144, step a (2.73 g, 81%) as a yellow solid which was used directly. R_(t)=2.01 min (Cond.-D1); 95% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₉H₅Cl₂N₂O₂: 242.97. found: 242.92.

Cap-144, step a (0.30 g, 1.23 mmol) was taken up in methanol (60 mL) and treated with platinum oxide (30 mg), and the suspension was subjected to Parr hydrogenation at 7 psi H₂ for 1.5 h before formalin (5 mL) and additional platinum oxide (30 mg) were added. The suspension was resubjected to Parr hydrogenation at 45 psi H₂ for 13 h before it was suction-filtered through diatomaceous earth (Celite®) and concentrated down to ¼ volume. Suction-filtration of the ensuing precipitate afforded the title compound as a yellow solid which was flash chromatographed on silica gel (gradient elution with 5% ethyl acetate in hexanes to 25% ethyl acetate in hexanes) to afford Cap-144, step b (231 mg, 78%) as a pale, yellow solid. R_(t)=2.36 min (Cond.-D1); 95% homogeneity index; ¹H NMR (400 MHz, CDCl₃) δ 8.02 (s, 1H), 7.95 (d, J=8.6 Hz, 1H), 7.57-7.53 (m, 1H), 7.30 (d, J=7.3 Hz, 1H), 2.88 (s, 6H); LCMS: Anal. Calc. for [M+H]⁺C₁H₁₁Cl₂N₂: 241.03. found: 241.02. HRMS: Anal. Calc. for [M+H]⁺C₁₁H₁₁Cl₂N₂: 241.0299. found: 241.0296.

Cap-144, step c was prepared from Cap-144, step b according to the procedure described for the preparation of Cap-139, step a. R₁=2.19 min (Cond.-D1); 95% homogeneity index; LCMS: Anal. Calc. for [M+H]⁺C₁₂H₁₁ClN₃: 232.06. found: 232.03. HRMS: Anal. Calc. for [M+H]⁺C₁₂H₁₁ClN₃: 232.0642. found: 232.0631.

Cap-144

Cap-144 was prepared according to the procedure described for Cap-141. R_(t)=2.36 min (Cond.-D1); 90%; LCMS: Anal. Calc. for [M+H]⁺ C₁₂H₁₂ClN₂O₂: 238.01. found: 238.09.

Caps-145 to −162

Caps-145 to 162 were prepared from the appropriate 1-chloroisoquinolines according to the procedure described for the preparation of Cap-138 (Method A) or Cap-139 (Method B) unless noted otherwise as outlined below.

R_(t) (LC- Cond.); % homogeneity index; Cap # Cap Method Hydrolysis MS data Cap- 145

B 12 N HCl 1.14 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇ClNO₂: 208.02; found: 208.00. Cap- 146

A 5 N NaOH 1.40 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₁₀NO₃: 204.07; found: 204.06. Cap- 147

B 5 N NaOH 0.87 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₁₀NO₃: 204.07; found: 204.05. Cap- 148

A 5 N NaOH 0.70 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₁₀NO₃: 204.07; found: 204.05. Cap- 149

A 5 N NaOH 0.70 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₁₀NO₃: 204.07; found: 204.05. Cap- 150

A 12 N HCl 0.26 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₁₀NO₃: 204.07; found: 204.04. Cap- 151

B 12 N HCl 1.78 min (Cond.- D1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₉ClNO₃: 238.03; found: 238.09. Cap- 152

B 12 N HCl 1.65 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₉ClNO₃: 238.00; found: 238.09. Cap- 153

A 6 N HCl 1.18 min (Cond.- MS-W1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇BrNO₂: 251.97; found: 251.95. Cap- 154

B 5 N NaOH 0.28 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇FNO₂: 192.05; found: 192.03. Cap- 155

B 5 N NaOH 0.59 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇ClNO₂: 208.02; found: 208.00. Cap- 156

B 5 N NaOH 0.60 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇ClNO₂: 208.02; found: 208.03. Cap- 157

B 12 N HCl 1.49 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₁₇ClNO: 208.02; found: 208.00. Cap- 158

B 5 N NaOH 0.69 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇ClNO₂: 208.02; found: 208.01. Cap- 159

B 5 N NaOH 0.41 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇FNO₂: 192.05; found: 192.03. Cap- 160

B 5 N NaOH 0.30 min (Cond.- MS-W1); 90%; LCMS: Anal. Calc. for [M + H]⁺ C₁₀H₇FNO₂: 192.05; found: 192.03. Cap- 161

— — 0.70 min (Cond.- D1); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₂H₁₃N₂O₂: 217.10; found: 217.06. Cap- 162

— — 0.65 min (Cond.- M3); 95%; LCMS: Anal. Calc. for [M + H]⁺ C₁₁H₁₀NO₃: 204.07; found: 203.94.

To a solution of 2-ketobutyric acid (1.0 g, 9.8 mmol) in diethylether (25 ml) was added phenylmagnesium bromide (22 ml, 1M in THF) dropwise. The reaction was stirred at ˜25° C. under nitrogen for 17.5 h. The reaction was acidified with 1N HCl and the product was extracted with ethyl acetate (3×100 ml). The combined organic layer was washed with water followed by brine and dried over MgSO₄. After concentration in vacuo, a white solid was obtained. The solid was recrystallized from hexanes/ethyl acetate to afford Cap-163 as white needles (883.5 mg). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): 12.71 (br s, 1H), 7.54-7.52 (m, 2H), 7.34-7.31 (m, 2H), 7.26-7.23 (m, 1H), 5.52-5.39 (br s, 1H), 2.11 (m, 1H), 1.88 (m, 1H), 0.79 (app t, J=7.4 Hz, 31-1).

A mixture of 2-amino-2-phenylbutyric acid (1.5 g, 8.4 mmol), formaldehyde (14 mL, 37% in water), 1N HCl (10 mL) and 10% Pd/C (0.5 mg) in MeOH (40 mL) was exposed to H₂ at 50 psi in a Parr bottle for 42 h. The reaction was filtered over Celite and concentrated in vacuo, the residue was taken up in MeOH (36 mL) and the product was purified with a reverse phase HPLC (MeOH/H₂O/TFA) to afford the TFA salt of Cap-164 as a white solid (1.7 g). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz) 7.54-7.47 (m, 5H), 2.63 (m, 1H), 2.55 (s, 6H), 2.31 (m, 1H), 0.95 (app t, J=7.3 Hz, 3H).

To a mixture of 2-amino-2-indanecarboxylic acid (258.6 mg, 1.46 mmol) and formic acid (0.6 ml, 15.9 mmol) in 1,2-dichloroethane (7 ml) was added formaldehyde (0.6 ml, 37% in water). The mixture was stirred at ˜25° C. for 15 min then heated at 70° C. for 8 h. The volatile component was removed in vacuo, and the residue was dissolved in DMF (14 mL) and purified by a reverse phase HPLC (MeOH/H₂O/TFA) to afford the TFA salt of Cap-165 as a viscous oil (120.2 mg). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): 7.29-7.21 (m, 4H), 3.61 (d, J=17.4 Hz, 2H), 3.50 (d, J=17.4 Hz, 2H), 2.75 (s, 6H). LC/MS: Anal. Calcd. for [M+H]⁺ C₁₂H₁₆NO₂: 206.12. found: 206.07.

Caps-166a and -166b were prepared from (1S,4S)-(+)-2-methyl-2,5-diazabicyclo[2.2.1]heptane (2HBr) according to the method described for the synthesis of Cap-7a and Cap-7b, with the exception that the benzyl ester intermediate was separated using a semi-prep Chrialcel OJ column, 20×250 mm, 10 μm eluting with 85:15 heptane/ethanol mixture at 10 mL/min elution rate for 25 min. Cap-166b: ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz): 7.45 (d, J=7.3 Hz, 2H), 7.27-7.19 (m, 3H), 4.09 (s, 1H), 3.34 (app br s, 1H), 3.16 (app br s, 1H), 2.83 (d, J=10.1 Hz, 1H), 2.71 (m, 2H), 2.46 (m, 1H), 2.27 (s, 3H), 1.77 (d, J=9.8 Hz, 1H), 1.63 (d, J=9.8 Hz, 1H). LC/MS: Anal. Calcd. for [M+H]⁺ C₁₀H₁₉N₂O₂: 247.14. found: 247.11.

A solution of racemic Boc-1,3-dihydro-2H-isoindole carboxylic acid (1.0 g, 3.8 mmol) in 20% TFA/CH₂Cl₂ was stirred at ˜25° C. for 4 h. All the volatile component was removed in vacuo. A mixture of the resultant crude material, formaldehyde (15 mL, 37% in water), 1N HCl (10 mL) and 10% Pd/C (10 mg) in MeOH was exposed to H₂ (40 PSI) in a Parr bottle for 23 h. The reaction mixture was filtered over Celite and concentrated in vacuo to afford Cap-167 as a yellow foam (873.5 mg). ¹H NMR (DMSO-d₆, δ=2.5 ppm, 500 MHz) 7.59-7.38 (m, 4H), 5.59 (s, 1H), 4.84 (d, J=14 Hz, 1H), 4.50 (d, J=14.1 Hz, 1H), 3.07 (s, 3H). LC/MS: Anal. Calcd. for [M+H]⁺C₁₀H₁₂NO₂: 178.09. found: 178.65.

Racemic Cap-168 was prepared from racemic Boc-aminoindane-1-carboxylic acid according to the procedure described for the preparation of Cap-167. The crude material was employed as such.

A mixture of 2-amino-2-phenylpropanoic acid hydrochloride (5.0 g, 2.5 mmol), formaldehyde (15 ml, 37% in water), 1N HCl (15 ml), and 10% Pd/C (1.32 g) in MeOH (60 mL) was placed in a Parr bottle and shaken under hydrogen (55 PSI) for 4 days. The reaction mixture was filtered through diatomaceous earth (Celite®) and concentrated in vacuo. The residue was taken up in MeOH and purified by reverse phase prep-HPLC (MeOH/water/TFA) to afford the TFA salt of Cap-169 as a viscous semi-solid (2.1 g). ¹H NMR (CDCl₃, δ=7.26 ppm, 500 MHz): 7.58-7.52 (m, 2H), 7.39-7.33 (m, 3H), 2.86 (br s, 3H), 2.47 (br s, 3H), 1.93 (s, 3H). LC/MS: Anal. Calcd. for [M+H]⁺C₁₁H₁₆NO₂: 194.12. found: 194.12.

To (S)-2-amino-2-(tetrahydro-2H-pyran-4-yl)acetic acid (505 mg; 3.18 mmol; obtained from Astatech) in water (15 ml) was added sodium carbonate (673 mg; 6.35 mmol), and the resultant mixture was cooled to 0° C. and then methyl chloroformate (0.26 ml; 3.33 mmol) was added dropwise over 5 minutes. The reaction was allowed to stir for 18 hours while allowing the bath to thaw to ambient temperature. The reaction mixture was then partitioned between 1N HCl and ethyl acetate. The organic layer was removed and the aqueous layer was further extracted to with 2 additional portions of ethyl acetate. The combined organic layers were washed with brine, dried over magnesium sulfate, filtered and concentrated in vacuo to afford Cap-170 a colorless residue. ¹H NMR (500 MHz, DMSO-d₆) δ ppm 12.65 (1H, br s), 7.44 (1H, d, J=8.24 Hz), 3.77-3.95 (3H, m), 3.54 (3H, s), 3.11-3.26 (2H, m), 1.82-1.95 (1H, m), 1.41-1.55 (2H, m), 1.21-1.39 (2H, m); LC/MS: Anal. Calcd. for [M+H]⁺ C₉H₁₆NO₅: 218.1. found 218.1.

A solution of methyl 2-(benzyloxycarbonylamino)-2-(oxetan-3-ylidene)acetate (200 mg, 0.721 mmol; Il Farmaco (2001), 56, 609-613) in ethyl acetate (7 ml) and CH₂Cl₂ (4.00 ml) was degassed by bubbling nitrogen for 10 min. Dimethyl dicarbonate (0.116 ml, 1.082 mmol) and Pd/C (20 mg, 0.019 mmol) were then added, the reaction mixture was fitted with a hydrogen balloon and allowed to stir at ambient temperature overnight at which time TLC (95:5 CH₂Cl₂/MeOH: visualized with stain made from 1 g Ce(NH₄)₂SO₄, 6 g ammonium molybdate, 6 ml sulfuric acid, and 100 ml water) indicated complete conversion. The reaction was filtered through celite and concentrated. The residue was purified via Biotage® (load with dichloromethane on 25 samplet; elute on 25S column with dichloromethane for 3CV then 0 to 5% MeOH/dichloromethane over 250 ml then hold at 5% MeOH/dichloromethane for 250 ml; 9 ml fractions). Collected fractions containing desired material and concentrated to 120 mg (81%) of methyl 2-(methoxycarbonylamino)-2-(oxetan-3-yl)acetate as a colorless oil. ¹H NMR (500 MHz, CHLOROFORM-D) δ ppm 3.29-3.40 (m, J=6.71 Hz, 1H) 3.70 (s, 3H) 3.74 (s, 3H) 4.55 (t, J=6.41 Hz, 1H) 4.58-4.68 (m, 2H) 4.67-4.78 (m, 2H) 5.31 (br s, 1H). LC/MS: Anal. Calcd. for [M+H]⁺ C₈H₁₄NO₅: 204.2. found 204.0.

To methyl 2-(methoxycarbonylamino)-2-(oxetan-3-yl)acetate (50 mg, 0.246 mmol) in THF (2 mL) and water (0.5 mL) was added lithium hydroxide monohydrate (10.33 mg, 0.246 mmol). The resultant solution was allowed to stir overnight at ambient temperature. TLC (1:1 EA/Hex; Hanessian stain [1 g Ce(NH₄)₂SO₄, 6 g ammonium molybdate, 6 ml sulfuric acid, and 100 ml water]) indicated ˜10% starting material remaining. Added an additional 3 mg LiOH and allowed to stir overnight at which time TLC showed no starting material remaining. Concentrated in vacuo and placed on high vac overnight providing 55 mg lithium 2-(methoxycarbonylamino)-2-(oxetan-3-yl)acetate as a colorless solid. ¹H NMR (500 MHz, MeOD) δ ppm 3.39-3.47 (m, 1H) 3.67 (s, 3H) 4.28 (d, J=7.93 Hz, 1H) 4.64 (t, J=6.26 Hz, 1H) 4.68 (t, J=7.02 Hz, 1H) 4.73 (d, J=7.63 Hz, 2H).

The following diazotization step was adapted from Barton, A.; Breukelman, S. P.; Kaye, P. T.; Meakins, G. D.; Morgan, D. J. J. C. S. Perkin Trans I 1982, 159-164: A solution of NaNO₂ (166 mg, 2.4 mmol) in water (0.6 mL) was added slowly to a stirred, cold (0° C.) solution of methyl 2-amino-5-ethyl-1,3-thiazole-4-carboxylate (186 mg, 1.0 mmol), CuSO₄.5H₂O (330 mg, 1.32 mmol), NaCl (260 mg, 4.45 mmol) and H₂SO₄ (5.5 mL) in water (7.5 mL). The mixture was stirred at 0° C. for 45 min and allowed to warm up to room temperature where it stirred further for 1 h before CuCl (118 mg) was added. This mixture was stirred further at room temperature for 16 h before it was diluted with brine and extracted with ether twice. The organic layers were combined, dried over MgSO₄ and concentrated to give methyl 2-chloro-5-ethylthiazole-4-carboxylate (i.e. Cap-172, step a) (175 mg, 85%) as an orange oil (80% pure) which was used directly in the next reaction. R_(t)=1.99 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₇H₉ClNO₂S: 206.01. found: 206.05.

Cap-172

To a solution of methyl 2-chloro-5-ethylthiazole-4-carboxylate (175 mg) in THF/H₂O/MeOH (20 mL/3 mL/12 mL) was added LiOH (305 mg, 12.76 mmol). The mixture was stirred at room temperature overnight before it was concentrated down and neutralized with 1N HCl in ether (25 mL). The residue was extracted twice with ethyl acetate and the organic layers were combined, dried over MgSO₄ and evaporated to yield Cap-172 (60 mg, 74%) as a red solid which was used without further purification. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 13.03-13.42 (1H, m), 3.16 (2H, q, J=7.4 Hz), 1.23 (3H, t, J=7.5 Hz). R_(t)=1.78 min (Cond.-MDI); LC/MS: Anal. Calcd. for [M+H]⁺C₆H₇ClNO₂S: 191.99. found: 191.99.

The following diazotization step was adapted from Barton, A.; Breukelman, S. P.; Kaye, P. T.; Meakins, G. D.; Morgan, D. J. J. C. S. Perkin Trans I 1982, 159-164: A solution of NaNO₂ (150 mg, 2.17 mmol) in water (1.0 mL) was added dropwise to a stirred, cold (0° C.) solution of methyl 2-amino-5-ethyl-1,3-thiazole-4-carboxylate (186 mg, 1.0 mmol) in 50% H₃PO₂ (3.2 mL). The mixture was stirred at 0° C. for 1 h and allowed to warm up to room temperature where it stirred further for 2 h. After recooling to 0° C., the mixture was treated slowly with a solution of NaOH (85 mg) in water (10 mL). The mixture was then diluted with saturated NaHCO₃ solution and extracted twice with ether. The organic layers were combined, dried over MgSO₄ and concentrated to give methyl 5-ethylthiazole-4-carboxylate (i.e. Cap-173, step a) (134 mg, 78%) as an orange oil (85% pure) which was used directly in the next reaction. R_(t)=1.58 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺ C₇H₁₀NO₂S: 172.05. found: 172.05.

Cap-173

To a solution of methyl 5-ethylthiazole-4-carboxylate (134 mg) in THF/H₂O/MeOH (18 mL/2.7 mL/11 mL) was added LiOH (281 mg, 11.74 mmol). The mixture was stirred at room temperature overnight before it was concentrated down and neutralized with 1N HCl in ether (25 mL). The residue was extracted twice with ethyl acetate and the organic layers were combined, dried over MgSO₄ and evaporated to yield Cap-173 (90 mg, 73%) as an orange solid which was used without further purification. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 12.74-13.04 (1H, m), 3.20 (2H, q, J=7.3 Hz), 1.25 (3H, t, J=7.5 Hz). R_(t)=1.27 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₆H₈NO₂S: 158.03. found: 158.04.

Triflic anhydride (5.0 g, 18.0 mmol) was added dropwise to a cold (0° C.) solution of methyl 3-hydroxypicolinate (2.5 g, 16.3 mmol) and TEA (2.5 mL, 18.0 mmol) in CH₂Cl₂ (80 mL). The mixture was stirred at 0° C. for 1 h before it was allowed to warm up to room temperature where it stirred for an additional 1 h. The mixture was then quenched with saturated NaHCO₃ solution (40 mL) and the organic layer was separated, washed with brine, dried over MgSO₄ and concentrated to give methyl 3-(trifluoromethylsulfonyloxy)picolinate (i.e. Cap-174, step a) (3.38 g, 73%) as a dark brown oil (>95% pure) which was used directly without further purification. ¹H NMR (300 MHz, CDCl₃) 8 ppm 8.72-8.79 (1H, m), 7.71 (1H, d, J=1.5 Hz), 7.58-7.65 (1H, m), 4.04 (3H, s). R_(t)=1.93 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₈H₇F₃NO₅S: 286.00. found: 286.08.

Cap-174

To a solution of methyl 3-(trifluoromethylsulfonyloxy)picolinate (570 mg, 2.0 mmol) in DMF (20 mL) was added LiCl (254 mg, 6.0 mmol), tributyl(vinyl)stannane (761 mg, 2.4 mmol) and bis(triphenylphosphine)palladium dichloride (42 mg, 0.06 mmol). The mixture was heated at 100° C. overnight before a saturated solution of KF (20 mL) was added to the reaction mixture at room temperature. This mixture was stirred for 4 h before it was filtered through diatomaceous earth (Celite®) and the pad was washed with ethyl acetate. The aqueous phase of the filtrate was then separated and concentrated down in vacuo. The residue was treated with 4N HCl in dioxanes (5 mL) and the resulting mixture was extracted with methanol, filtered and evaporated to afford Cap-174 (260 mg) as a green solid which was slightly contaminated with inorganic salts but was used without further purification. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 8.21 (1H, d, J=3.7 Hz), 7.81-7.90 (1H, m), 7.09 (1H, dd, J=7.7, 4.8 Hz), 6.98 (1H, dd, J=17.9, 11.3 Hz), 5.74 (1H, dd, J=17.9, 1.5 Hz), 5.20 (1H, J=11.0 Hz). R_(t)=0.39 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₈H₈NO₂: 150.06. found: 150.07.

To a solution of methyl 3-(trifluoromethylsulfonyloxy)picolinate (i.e. Cap 173, step a) (570 mg, 2.0 mmol), an intermediate in the preparation of Cap-174, in DMF (20 mL) was added LiCl (254 mg, 6.0 mmol), tributyl(vinyl)stannane (761 mg, 2.4 mmol) and bis(triphenylphosphine)palladium dichloride (42 mg, 0.06 mmol). The mixture was heated at 100° C. for 4 h before the solvent was removed in vacuo. The residue was taken up in acetonitrile (50 mL) and hexanes (50 mL) and the resulting mixture was washed twice with hexanes. The acetonitrile layer was then separated, filtered through Celite, and evaporated. Purification of the residue by flash chromatography on a Horizon instrument (gradient elution with 25% ethyl acetate in hexanes to 65% ethyl acetate in hexanes) afforded methyl 3-vinylpicolinate (i.e. Cap-175, step a) (130 mg, 40%) as a yellow oil. ¹H NMR (300 MHz, CDCl₃) δ ppm 8.60 (1H, dd, J=4.6, 1.7 Hz), 7.94 (1H, d, J=7.7 Hz), 7.33-7.51 (2H, m), 5.72 (1H, d, J=17.2 Hz), 5.47 (1H, d, J=11.0 Hz), 3.99 (3H, s). R_(t)=1.29 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₉H₁₀NO₂: 164.07. found: 164.06.

Palladium on carbon (10%, 25 mg) was added to a solution of methyl 3-vinylpicolinate (120 mg, 0.74 mmol) in ethanol (10 mL). The suspension was stirred at room temperature under an atmosphere of hydrogen for 1 h before it was filtered through Celite and the pad of diatomaceous earth (Celite®) was washed with methanol. The filtrate was concentrated down to dryness to yield methyl 3-ethylpicolinate (i.e. Cap-175, step b) which was taken directly into the next reaction. R_(t)=1.15 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₉H₁₂NO₂: 166.09. found: 166.09.

Cap-175

To a solution of methyl 3-ethylpicolinate in THF/H₂O/MeOH (5 mL/0.75 mL/3 mL) was added LiOH (35 mg, 1.47 mmol). The mixture was stirred at room temperature for 2 d before additional LiOH (80 mg) was added. After an additional 24 h at room temperature, the mixture was filtered and the solvent was removed in vacuo. The residue was then treated with 4N HCl in dioxanes (5 mL) and the resulting suspension was concentrated down to dryness to yield Cap-175 as a yellow solid which was used without further purification. ¹H NMR (300 MHz, DMSO-d₆) δ ppm 8.47 (1H, dd, J=4.8, 1.5 Hz), 7.82-7.89 (1H, m), 7.53 (1H, dd, J=7.7, 4.8 Hz), 2.82 (2H, q, J=7.3 Hz), 1.17 (3H, t, J=7.5 Hz). R_(t)=0.36 min (Cond.-MD1); LC/MS: Anal. Calcd. for [M+H]⁺C₈H₁₀NO₂: 152.07. found: 152.10.

A solution of 1,4-dioxaspiro[4.5]decan-8-one (15 g, 96 mmol) in EtOAc (150 mL) was added to a solution of methyl 2-(benzyloxycarbonylamino)-2-(dimethoxyphosphoryl)acetate (21.21 g, 64.0 mmol) in 1,1,3,3-tetramethylguanidine (10.45 mL, 83 mmol) and EtOAc (150 mL). The resulting solution was the stirred at ambient temperature for 72 h and then it was diluted with EtOAc (25 mL). The organic layer was washed with 1N HCl (75 mL), H₂O (100 mL) and brine (100 mL), dried (MgSO₄), filtered and concentrated. The residue was purified via Biotage (5% to 25% EtOAc/Hexanes; 300 g column). The combined fractions containing the product were then concentrated under vacuum and the residue was re-crystallized from hexanes/EtOAc to give white crystals that corresponded to methyl 2-(benzyloxycarbonylamino)-2-(1,4-dioxaspiro[4.5]decan-8-ylidene)acetate (6.2 g) ¹H NMR (400 MHz, CDCl₃-d) δ ppm 7.30-7.44 (5H, m), 6.02 (1H, br. s.), 5.15 (2H, s), 3.97 (4H, s), 3.76 (3H, br. s.), 2.84-2.92 (2H, m), 2.47 (2H, t, J=6.40 Hz), 1.74-1.83 (4H, m). LC (Cond. OL1): R_(t)=2.89 min. LC/MS: Anal. Calcd. For [M+Na]⁺C₁₉H₂₃NNaO₆: 745.21. found: 745.47

Ester Cap 176, step b was prepared from alkene Cap 176, step a according to the method of Burk, M. J.; Gross, M. F. and Martinez J. P. (J. Am. Chem. Soc., 1995, 117, 9375-9376 and references therein): A 500 mL high-pressure bottle was charged with alkene Cap 176, step a (3.5 g, 9.68 mmol) in degassed MeOH (200 mL) under a blanket of N₂. The solution was then charged with (−)-1,2-Bis((2S,5S)-2,5-dimethylphospholano)ethane(cyclooctadiene)rhodium (I) tetrafluoroborate (0.108 g, 0.194 mmol) and the resulting mixture was flushed with N₂ (3×) and charged with H₂ (3×). The solution was shaken vigorously under 70 psi of H₂ at ambient temperature for 72 h. The solvent was removed under reduced pressure and the remaining residue was taken up in EtOAc. The brownish solution was then filtered through a plug of Silica Gel and eluted with EtOAc. The solvent was concentrated under vacuum to afford a clear oil corresponding to ester Cap 176, step b (3.4 g). ¹H NMR (500 MHz, CDCl₃-d) δ ppm 7.28-7.43 (5H, m), 5.32 (1H, d, J=9.16 Hz), 5.06-5.16 (2H, m), 4.37 (1H, dd, J=9.00, 5.04 Hz), 3.92 (4H, t, J=3.05 Hz), 3.75 (3H, s), 1.64-1.92 (4H, m), 1.37-1.60 (5H, m). LC (Cond. OL1): R_(t)=1.95 min. LC/MS: Anal. Calcd. For [M+H]⁺C₁₉H₂₆NO₆: 364.18. found: 364.27.

Ester Cap 176, step b (4.78 g, 13.15 mmol) was dissolved in THF (15 mL) followed by sequential addition of water (10 mL), glacial acetic acid (26.4 mL, 460 mmol) and dichloroacetic acid (5.44 mL, 65.8 mmol). The resulting mixture was stirred for 72 h at ambient temperature, and the reaction was quenched by slow addition of solid Na₂CO₃ with vigorous stirring until the release of gas was no longer visible. Crude product was extracted into 10% ethyl acetate-dichloromethane and the organic layers were combined, dried (MgSO₄) filtered and concentrated. The resulting residue was purified via Biotage (0 to 30% EtOAc/Hex; 25 g column) to afford ketone Cap 176, step c (3.86 g) as a clear oil. ¹H NMR (400 MHz, CDCl₃-d) δ ppm 7.28-7.41 (5H, m), 5.55 (1H, d, J=8.28 Hz), 5.09 (2H, s), 4.46 (1H, dd, J=8.16, 5.14 Hz), 3.74 (3H, s), 2.18-2.46 (5H, m), 1.96-2.06 (1H, m), 1.90 (1H, ddd, J=12.99, 5.96, 2.89 Hz), 1.44-1.68 (2H, m, J=12.36, 12.36, 12.36, 12.36, 4.77 Hz). LC (Cond. OL1): R_(t)=1.66 min. LC/MS: Anal. Calcd. For [M+Na]⁺ C₁₇H₂₁NNaO₅: 342.13. found: 342.10.

Deoxo-Fluor® (3.13 mL, 16.97 mmol) was added to a solution of ketone Cap 176, step c (2.71 g, 8.49 mmol) in CH₂Cl₂ (50 mL) followed by addition of a catalytic amount of EtOH (0.149 mL, 2.55 mmol). The resulting yellowish solution was stirred at rt overnight. The reaction was quenched by addition of sat. aq. NaHCO₃ (25 mL) and the mixture was extracted with EtOAc (3×75 mL)). The combined organic layers were dried (MgSO₄), filtered and dried to give a yellowish oil. The residue was purified via Biotage chromatography (2% to 15% EtOAc/Hex; 90 g column) and a white solid corresponding to the difluoro amino acid dilforide Cap 176, step d (1.5 g) was recovered. ¹H NMR (400 MHz, CDCl₃-d) δ ppm 7.29-7.46 (5H, m), 5.34 (1H, d, J=8.28 Hz), 5.12 (2H, s), 4.41 (1H, dd, J=8.66, 4.89 Hz), 3.77 (3H, s), 2.06-2.20 (2H, m), 1.83-1.98 (1H, m), 1.60-1.81 (4H, m), 1.38-1.55 (2H, m). ¹⁹F NMR (376 MHz, CDCl₃-d) δ ppm −92.15 (1F, d, J=237.55 Hz), −102.44 (1F, d, J=235.82 Hz). LC (Cond. OL1): R_(t)=1.66 min. LC/MS: Anal. Calcd. For [2M+Na]⁺C₃₄H₄₂F₄N₂NaO₈: 705.28. found: 705.18.

Difluoride Cap 176, step d (4 g, 11.72 mmol) was dissolved in MeOH (120 mL) and charged with Pd/C (1.247 g, 1.172 mmol). The suspension was flushed with N₂ (3×) and the reaction mixture was placed under 1 atm of H₂ (balloon). The mixture was stirred at ambient temperature for 48 h. The suspension was then filtered though a plug of Celite and concentrated under vacuum to give an oil that corresponded to amino acid Cap 176, step e (2.04 g) and that was used without further purification. ¹H NMR (400 MHz, DMSO-d₆) δ ppm 3.62 (3H, s), 3.20 (1H, d, J=5.77 Hz), 1.91-2.09 (2H, m), 1.50-1.88 (7H, m), 1.20-1.45 (2H, m). ¹⁹F NMR (376 MHz, DMSO-d₆) δ ppm −89.39 (1F, d, J=232.35 Hz), −100.07 (1F, d, J=232.35 Hz). ¹³C NMR (101 MHz, DMSO-d₆) 8 ppm 175.51 (1C, s), 124.10 (1C, t, J=241.21, 238.90 Hz), 57.74 (1C, s), 51.39 (1C, s), 39.23 (1C, br. s.), 32.02-33.83 (2C, m), 25.36 (1C, d, J=10.02 Hz), 23.74 (1C, d, J=9.25 Hz). LC (Cond. OL2): R_(t)=0.95 min. LC/MS: Anal. Calcd. For [2M+H]⁺ C₁₈H₃₁F₄N₂O₂: 415.22. found: 415.40.

Methyl chloroformate (1.495 mL, 19.30 mmol) was added to a solution of amino acid Cap 176, step e (2 g, 9.65 mmol) and DIEA (6.74 mL, 38.6 mmol) in CH₂Cl₂ (100 mL). The resulting solution was stirred at rt for 3 h and volatiles were removed under reduced pressure. The residue was purified via Biotage (0% to 20% EtOAc/Hex; 90 g column). A clear oil that solidified upon standing under vacuum and corresponding to carbamate Cap-176, step f (2.22 g) was recovered. ¹H NMR (500 MHz, CDCl₃-d) δ ppm 5.27 (1H, d, J=8.55 Hz), 4.39 (1H, dd, J=8.85, 4.88 Hz), 3.77 (3H, s), 3.70 (3H, s), 2.07-2.20 (2H, m), 1.84-1.96 (1H, m), 1.64-1.82 (4H, m), 1.39-1.51 (2H, m). ¹⁹F NMR (471 MHz, CDCl₃-d) 8 ppm −92.55 (1F, d, J=237.13 Hz), −102.93 (1F, d, J=237.12 Hz). ¹³C NMR (126 MHz, CDCl₃-d) δ ppm 171.97 (1C, s), 156.69 (1C, s), 119.77-125.59 (1C, m), 57.24 (1C, br. s.), 52.48 (1C, br. s.), 52.43 (1C, s), 39.15 (1C, s), 32.50-33.48 (2C, m), 25.30 (1C, d, J=9.60 Hz), 24.03 (1C, d, J=9.60 Hz). LC (Cond. OL1): R_(t)=1.49 min. LC/MS: Anal. Calcd. For [M+Na]⁺ C₁₁H₁₇F₂NNaO₄: 288.10. found: 288.03.

Cap-176

A solution of LiOH (0.379 g, 15.83 mmol) in water (25 mL) was added to a solution of carbamate Cap-176, step f (2.1 g, 7.92 mmol) in THF (75 mL) and the resulting mixture was stirred at ambient temperature for 4 h. THF was removed under vacuum and the remaining aqueous phase was acidified with 1N HCl solution (2 mL) and then extracted with EtOAc (2×50 mL). The combined organic layers were dried (MgSO₄), filtered and concentrated to give a white foam corresponding to Cap-176 (1.92 g). ¹H NMR (400 MHz, DMSO-d₆) δ ppm 12.73 (1H, s), 7.50 (1H, d, J=8.78 Hz), 3.97 (1H, dd, J=8.53, 6.02 Hz), 3.54 (3H, s), 1.92-2.08 (2H, m), 1.57-1.90 (5H, m), 1.34-1.48 (1H, m), 1.27 (1H, qd, J=12.72, 3.26 Hz). ¹⁹F NMR (376 MHz, DMSO-d₆) 8 ppm −89.62 (1F, d, J=232.35 Hz), −99.93 (1F, d, J=232.35 Hz). LC (Cond. OL2): R₄=0.76 min. LC/MS: Anal. Calcd. For [M−H]⁺ C₁₀H₁₄F₂NO₄: 250.09. found: 250.10.

EXAMPLES

The present disclosure will now be described in connection with certain embodiments which are not intended to limit its scope. On the contrary, the present disclosure covers all alternatives, modifications, and equivalents as can be included within the scope of the claims. Thus, the following examples, which include specific embodiments, will illustrate one practice of the present disclosure, it being understood that the examples are for the purposes of illustration of certain embodiments and are presented to provide what is believed to be the most useful and readily understood description of its procedures and conceptual aspects.

Solution percentages express a weight to volume relationship, and solution ratios express a volume to volume relationship, unless stated otherwise. Nuclear magnetic resonance (NMR) spectra were recorded either on a Bruker 300, 400, or 500 MHz spectrometer; the chemical shifts (8) are reported in parts per million.

Low resolution mass analysis and purity assessment were conducted on a Shimadzu LC system coupled with Waters Micromass ZQ MS system (Condition 1 & 1a) or Waters Acquity HPLC with Waters PDA UV-Vis detection and Waters ZQ MS (Condition 2). Retention time (R_(t)) were derived by employing the following conditions, and it should be noted that retention times may vary slightly between instruments:

Condition 1 Column=Phenomenex-Luna 3.0×50 mm S10 Start % B=0 Final % B=100

Gradient time=3 min Stop time=4 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Condition 1a Column=Phenomenex-Luna 4.6×30 mm S10 Start % B=0 Final % B=100

Gradient time=3 min Stop time=4 min Flow Rate=4 mL/min

Wavelength=220 nm

Solvent A=0.1% TFA in 10% methanol/90% H₂O Solvent B=0.1% TFA in 90% methanol/10% H₂O

Condition 2 Column=Waters Acquity BEH C18; 1.7 μm; 150×2.1 mm ID; (at 35 C) Hold 10% B 0-1 min 10-50% B 0-25 min 50-98% B 25-33 min Hold 98% B 32-35 min 98-10% B 35.0-35.5 min Hold 10% B 35.5-40 min

Flow rate=0.35 ml/min

Wavelength=254 nm

Solvent A=0.05% TFA in water

Solvent B=0.05% TFA in CH₃CN

Homogeneity index assessments were made on a Shimadzu LC system coupled under the following conditions:

Condition 3 Column=Waters Sunfire C18, 4.6×150 mm, 3.5 μm Start % B=10 Final % B=50

Gradient time=20 min Stop time=25 min Flow Rate=1 mL/min

Wavelength=220 & 254 nm Solvent A=0.1% TFA in 5% CH₃CN/95% H₂O Solvent B=0.1% TFA in 95% CH₃CN/5% H₂O Condition 3a

Same as Condition 3 with the exception that the Stop time=50 min.

Condition 4

Column=Waters Xbridge phenyl, 4.6×150 mm, 3 μm

Start % B=10 Final % B=50

Gradient time=20 min Stop time=25 min Flow Rate=1 mL/min

Wavelength=220 & 254 nm Solvent A=0.1% TFA in 5% CH₃CN/95% H₂O Solvent B=0.1% TFA in 95% CH₃CN/5% H₂O Condition 4a

Same as Condition 4 with the exception that Stop time=40 min.

Example 1

Example 1 Step a

DMAP (2.833 g, 23.19 mmol) was added to a CH₂Cl₂ (40 mL) solution of (S)-methyl 4,5-dihydro-1H-pyrazole-5-carboxylate (prepared according to J. Am. Chem. Soc. 1997, 119, 8379-8380; 2.95 g, 23.02 mmol) and Boc₂O (11.89 mL, 51.2 mmol), and stirred at ambient condition for 22.5 hr. An additional Boc₂O (1.83 g) was added and stirring was continued for 15 hr. Silica gel was added to the reaction mixture and the solvent was removed in vacuo, and the resultant mesh was submitted to a Biotage purification (300 g silica gel; column was eluted with 30-50% EtOAc/hexanes) to afford carbamate 1a as a yellow oil (3.956 g). A sample of the starting pyrazoline, contaminated with the product, was also retrieved (695 mg). ¹H NMR (CDCl₃, δ=7.24 ppm, 400 MHz): 6.80 (s, 1H), 4.67 (dd, J=12.6, 6.1 Hz, 1H), 3.75 (s, 3H), 3.22 (ddd, J=18.5, 12.6, 1.4 Hz, 1H), 2.94 (ddd, J=18.5, 6.1, 1.7 Hz, 1H), 1.5 (s, 9H). LC/MS: Anal. Calcd. for [M+Na]⁺ C₁₀H₁₆N₂NaO₄: 251.10. found 251.26.

Example 1 Step b

Sodium cyanoborohydride (0.769 g, 12.23 mmol) was added in batches over 1 min to an acetic acid (7.0 mL) solution of carbamate 1a (1.0523 g, 4.61 mmol), and stirred at ambient condition for 20 h. Formaldehyde (1 mL of 37% in water) was added drop-wise over 4 min, and stirring was continued for 4.5 h. The volatile component was removed in vacuo and the residue was treated with saturated NaHCO₃ (10 mL) and CH₂Cl₂ (30 mL), and the mixture was shaken and the phases were separated. The organic layer was washed with an additional saturated NaHCO₃ solution (10 mL), dried (MgSO₄) and concentrated in vacuo. The resultant crude material was purified with a Biotage (240 g silica gel; sample was loaded with CH₂Cl₂; eluted with 60-100% EtOAc/hexanes) to afford carbamate 1b as a colorless oil (861 mg). ¹H NMR (CDCl₃, δ=7.24 ppm, 400 MHz): 4.39 (app br t, J=7.7, 1H), 3.74 (s, 3H), 3.15-3.02 (m, 2H), 2.64 (s, 3H), 2.48-2.40 (m, 1H), 2.30-2.21 (m, 1H), 1.45 (s, 9H). LC/MS: Anal. Calcd. for [M+Na]⁺C₁₁H₂₀N₂NaO₄: 267.13. found 267.28.

Example 1 Step c

A water (5 mL) solution of LiOH (0.1459 g, 6.09 mmol) was added to a methanol (5 mL) solution of ester 1b (0.76 g, 3.11 mmol), and stirred at ambient conditions for ˜7 h. The reaction mixture was cooled with an ice-water bath, and HCl/H₂O (3 mL of 1.00 N; 3.0 mmol) was added drop-wise and stirred for a few minutes. Then, the volatile component was removed in vacuo and the resultant viscous oil was exposed to high vacuum to afford carboxylate 1c as a white foam, which was employed as such for the next step. ¹H NMR (DMSO-do, δ=2.50 ppm, 400 MHz) for crude sample: 3.98 (dd, J=8.5, 6.3, 1H), 2.86-2.74 (m, 2H), 2.45 (s, 3H), 2.25-2.17 (m, 1H), 2.10-2.02 (m, 1H), 1.35 (s, 9H). LC/MS: Anal. Calcd. for [M+H]⁺C₁₀H₁₉N₂O₄: 231.13. found 231.21.

Example 1 Step d

1,1′-(biphenyl-4,4′-diyl)bis(2-bromoethanone) (0.601 g, 1.517 mmol) was added in one batch to a DMF (10 mL) solution of carboxylate is (3.1 mmol) and DIEA (0.55 mL, 3.15 mmol), and the resulting heterogeneous mixture was stirred at ambient condition for ˜20.6 h, after which it attained a homogeneous appearance. The volatile component was removed in vacuo, and the residue was partitioned between CH₂Cl₂ (100 mL), water (20 mL) and saturated NaHCO₃ solution (1 mL). An unusually milky looking organic layer was retrieved which required more than usual amount of MgSO₄ to dry. The organic layer was concentrated in vacuo, and the resulting residue was submitted to a Biotage purification (110 g silica gel; CH₂Cl₂ was used to load the sample; 50-100% EtOAc/hexanes to remove higher R_(f) impurities, followed by 10% MeOH/EtOAc) to afford diester 1d as a yellow foam (808 mg). ¹H NMR analysis indicated that the sample contains residual solvents in a 1.0:0.2:0.1 product/DMF/EtOAc mole ratio, and that minor unidentified impurities are present according to LC/MS analysis. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 8.11 (d, J=8.3, 4H), 7.97 (d, J=8.6, 4H), 5.68 (d, J=17.1, 2H), 5.57 (d, J=16.9, 2H), 4.51 (dd, J=8.9, 6.4, 2H), 3.05-2.95 (m, 4H), 2.64-2.55 (m, 2H), 2.48 (s, 6H), 2.45-2.37 (m, 2H), 1.39 (s, 18H). LC/MS: Anal. Calcd. for [M+H]⁺ C₃₆H₄₇N₄O₁₀: 695.33. found 695.35.

Example 1 Step e

Ammonium acetate (1.75 g, 22.7 mmol) was added to a Xylene (11 mL) solution of ketoester 1d (802 mg), and the reaction flask was capped and heated with a microwave at 140° C. for 90 min to afford a reddish heterogeneous mixture with a dark red tar settled at the bottom of the reaction flask. The reaction mixture was treated with CH₂Cl₂ (90 mL), MeOH (3 mL), water (60 mL), saturated NaHCO₃ (6 mL), and stirred vigorously to effect total dissolution and then the phases were separated. The aqueous layer was washed with CH₂Cl₂ (45 mL), and the combined organic phase was dried (MgSO₄) and concentrated in vacuo. The residual material was dissolved in MeOH and purified with a reverse phase HPLC (H₂O/MeOH/TFA), and the HPLC elute was treated with excess 2 N NH₃/MeOH to quench the TFA. The volatile component was removed in vacuo, and the resulting material was partitioned between 10% MeOH/CH₂Cl₂ (60 mL), water (20 mL), and saturated NaHCO₃ (2 mL). The aqueous phase was then washed with 20% MeOH/CHCl₃ (25 mL) to help solubilize the solid suspension. The combined organic phase was dried (MgSO₄) and evaporated in vacuo to afford imidazole 1e as an off-white solid (287 mg; ¹H NMR analysis indicated that the sample contains ˜1 mol. equiv. of MeOH). (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.34 (br s, 0.36H), 11.88 (br s, 1.64H), 7.85-7.64 (m, 8H), 7.54-7.52 (m, 1.62H), 7.37-7.35 (m, 0.38H), 4.94-4.89 (m, 2H), 3.14-3.08 (m, 2H), 3.05-2.98 (m, 2H), 2.62 (br s, 6H), ˜2.47 (m, 4H; partially overlapped with solvent signal), 1.30/1.26 (2 partially overlapped s, 181-1). LC/MS: Anal. Calcd. for [M+H]⁺ C₃₆H₄₇N₈O₄: 655.37. found 655.28.

Example 1 Step f

4.0 N HCl/dioxane (5 mL, 20 mmol) and MeOH (1 mL) were added sequentially to carbamate 1e (276 mg), and the mixture was stirred at ambient condition for 4.5 h. The volatile component was removed in vacuo to afford the HCl salt of pyrazolidine if as off-white solid (270 mg), which was submitted to the next step without purification. ¹H NMR analysis indicated the sample contained minor unidentified impurities. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 8.20 (s, 2H), 8.07 (d, J=8.3, 4H), 7.94 (d, J=8.6, 4H), 7.55 (br s, ˜1.6H), 5.17 (br s, 2H), 3.06 (s, 6H), 2.93-2.64 (br m, 4H) (Note: the signals of CH₂N could not be discerned in part due to signal broadening and overlapping with that of water). LC/MS: Anal. Calcd. for [M+H]⁺ C₂₆H₃₁N₈: 455.27. found 455.17.

Example 1

DIEA (0.14 mL, 0.802 mmol) was added to a mixture of pyrazolidine if (81 mg, 0.12 mmol), (S)-2-(methoxycarbonylamino)-3-methylbutanoic acid (0.049 mg, 0.281 mmol) and HATU (97.7 mg, 0.257 mmol) in DMF (2 mL), and the resultant reaction mixture was stirred at room temperature for 36 min. Most of the volatile component was removed in vacuo, and the residue was purified with two different reverse phase HPLC conditions (MeOH/water/TFA followed by CH₃CN/water/TFA) to afford the TFA salt of Example 1 as an off-white foam (30.3 mg). ¹H NMR (DMSO-d₆ spiked with D₂O, δ=2.50 ppm, 400 MHz): 8.13-7.96 (br m, 2H), 7.91 (app s, 8H), 5.29 (m, 2H), 4.71/4.52 (two overlapping br s, 2H), 3.52 (s, 6H), 3.25-2.90 (br m, 4.66H), 2.82-2.59 (overlapping of m & s, s is at 2.66, 8.34H), 2.35-2.23 (m, 1H), 2.13-2.04 (m, 2H), 0.92-0.67 (overlapped br m, 12H). LC (Condition 3 & 4): >95% homogeneity index. LC/MS (Condition 1): R_(t)=1.80 min. LC/MS: Anal. Calcd. for [M+H]⁺ C₄₀H₅₃N₁₀O₆: 769.41. found 769.34.

Example 2-6

Example 2-4 were prepared as TFA salts from intermediate if and appropriate acids according to the procedure described for the synthesis of Example 1. Example 5 was isolated during the preparation of Example 4, presumably resulting from an epimerization of the benzylic center during the coupling step. Example 6 (TFA salt) was prepared similarly from intermediate if by employing an equimolar mixture of (S)-2-(methoxycarbonylamino)-3-methylbutanoic acid and (5)-2-(methoxycarbonylamino)-2-(tetrahydro-2H-pyran-4-yl)acetic acid for the coupling step and separating the resultant statistical mixture of products by the HPLC technique that is described for Example-1.

Example

R_(t) (Condition 1 for Ex. 4 & 5; Condition 1a for Ex. 2, 3 & 6); homogeneity index (Condition 3 & 4) MS data 2

1.56 min; >95% LC/MS: Anal. Calcd. for [M + H]⁺ C₄₄H₅₇N₁₀O₈: 853.44; found 853.51. 3

1.71 min; >95% LC/MS: Anal. Calcd. for [M + H]⁺ C₃₈H₄₉N₁₀O₆: 741.38; found 741.50. 4

1.91 min; >95% LC/MS: Anal. Calcd. for [M + H]⁺ C₄₆H₄₉N₁₀O₆: 837.38; found 837.31. 5

1.92 min; >95% LC/MS: Anal. Calcd. for [M + H]⁺ C₄₆H₄₉N₁₀O₆: 837.38; found 837.31. 6

1.73; >95% LC/MS: Anal. Calcd. for [M + H]⁺ C₄₂H₅₅N₁₀O₇: 811.43; found 811.43.

Example 7

Example 3 (TFA salt; 45.6 mg; 0.047 mmol) was free-based (1 g MCX; MeOH wash; 2.0 M NH₃/MeOH elution), and the elute was concentrated and exposed to high vacuum for ˜2 hr. NCS (0.0153 g, 0.112 mmol) and DMF (1.5 mL) were added to the above material, and the reaction mixture was heated at 50° C. for ˜21 hr. After it was allowed to cool to room temperature, it was diluted with MeOH and purified with a reverse phase HPLC (MeOH/water/TFA) to afford the TFA salt of Example 7 as a light-yellow foam (32.7 mg). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 7.88-7.82 (m, 8H), 7.27-6.89 (two br m, 2H), 5.12-4.98 (br m, 2H), 4.70 (br m, 1.52H), 4.46 (br m, 0.48H), 3.56-2.50 (two ‘s’ overlapped with ‘m’, 19.5H), 2.03 (br m, 0.5H), 1.74-1.38 (m, 4H), 0.90 (m, 6H). LC (Condition 3a & 4a): >95% homogeneity index. LC/MS (Condition 1a): R_(t)=2.87 min. LC/MS: Anal. Calcd. for [M+H]⁺C₃₈H₄₇Cl₂N₁₀O₆: 809.31. found 809.29.

Example 7.1

Example 7.1 (TFA salt) was prepared from Example 1 according to the procedure described for the preparation of Example 7. LC (Condition 3a & 4a): >95% homogeneity index. LC/MS (Condition 1a): R_(t)=2.99 min. LC/MS: Anal. Calcd. for [M+H]⁺C₄₀H₅₁Cl₂N₁₀O₆: 837.34. found 837.34.

Example 8

Example 8 Step a

A water (1.5 mL) solution of LiOH (0.030 g, 1.25 mmol) was added to a MeOH (1.5 mL) solution of ester 1b (0.157 g, 0.643 mmol), and stirred at room temperature for 3.5 h. Most of the volatile component was removed in vacuo and the residue was diluted with water (10 mL), 1.3 mL of 1N HCl was added dropwise, and then was extracted with EtOAc (25 mL, 4×). The combined organic phase was dried (MgSO₄) and evaporated in vacuo to afford acid 8a as a colorless oil, which solidified partially upon extended exposure to high vacuum (115.8 mg). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 4.19 (dd, J=8.8, 6.8, 1H), 2.96-2.86 (m, 2H), 2.47-2.39 [overlapped (m, 1H) & (s, 3H)], 2.16-2.07 (m, 1H), 1.36 (s, 9H). [Note that the ¹H NMR profile is different from that of its lithium carboxylate analog 1c.]

Example 8 Step b

DIEA (0.45 mL, 2.58 mmol) was added drop-wise over 30 second to a mixture of 2-amino-1-(4-bromophenyl)ethanone hydrochloride (0.218 g, 0.871 mmol), acid 8a (0.20 g, 0.87 mmol) and HATU (0.331 g, 0.871 mmol) in DMF (3 mL), and the resultant solution was stirred at room temperature for 130 min. Most of the DMF was removed in vacuo, and the residue was partitioned between CH₂Cl₂ (50 mL) and water (20 mL). The organic layer was dried (MgSO₄) and concentrated in vacuo. The crude material was purified with a Biotage (90 g silica gel; sample was loaded with the assistance of CH₂Cl₂; EtOAc elution) to afford ketoamide 8b as an off-white solid (317 mg). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 8.25 (app br t, J=5.6, 1H), 7.93 (d, J=8.6, 2H), 7.76 (d, J=8.5, 2H), 4.67 (dd, J=18.4, 5.8, 1H), 4.56 (dd, J=18.4, 5.5, 1H), 4.34 (dd, J=8.5, 6.8, 1H), 2.90 (m, 2H), 2.47 (s, 3H), 2.40-2.32 (m, 1H), 2.16-2.08 (m, 1H), 1.37 (s, 91-1). LC/MS: Anal. Calcd. for [M+Na]⁺ C₁₈H₂₅ ⁸¹BrN₃NaO₄: 450.08. found 450.07.

Example 8 Step c

Ammonium acetate (0.388 g, 5.03 mmol) was added to a 15 mL pressure tube containing a mixture of ketoamide 8b (0.313 g, 0.734 mmol) and xylenes (7.0 mL), and the pressure tube was capped and heated with an oil bath equilibrated between 133-135° C. for 130 min. Most of the volatile component was removed in vacuo, and the residue was partitioned between CH₂Cl₂ (50 mL), water (20 mL) and saturated NaHCO₃ solution (2 mL). The organic layer was dried (MgSO₄), concentrated in vacuo and purified with a Biotage (40 g silica gel; sample was loaded onto column with CH₂Cl₂; EtOAc elution) to afford imidazole 8c as a dark yellow solid (202 mg). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.36 (br s, 0.11H), 11.93 (br s, 0.89H), 7.71-7.49 (m, 5H), 4.89 (app t, J=7.6, 1H), 3.11-2.97 (m, 2H), 2.60 (s, 3H), ˜2.46 (br m, partially overlapped with solvent signal, 2H), 1.29/1.25 (two overlapped s, 9H). LC/MS: Anal. Calcd. for [M+H]⁺C₁₈H₂₄ ⁸¹BrN₄O₄: 409.11. found 409.11.

Example 8 Step d

Pd(Ph₃P)₄ (0.025 g, 0.022 mmol) was added to a DMF (3 mL) solution of bromide 8c (0.19 g, 0.466 mmol) and 1,2-bis(trimethylstannyl)ethyne (0.081 g, 0.230 mmol) in a vial. Nitrogen was bubbled through the reaction mixture for 1.5 min, and the vial was capped and heated at 90° C. behind a blast-shield for 16.5 hr. Most of the volatile component was removed in vacuo, and the residue was purified with a Biotage (30 g silica gel; 0-30% MeOH/EtOAc) to afford alkyne 8d, containing residual solvent and minor unidentified impurity, as a yellow foam/solid (108 mg). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.41 (s, 0.26H), 11.97 (s, 1.74H), 7.81-7.40 (m, 10H), 4.90 (app t, J=7.7, 2H), 3.13-2.98 (m, 4H), 2.61 (s, 6H), ˜2.47 (m, partially overlapped with solvent signal, 4H), 1.30/1.26 (two overlapped s, 18H). LC/MS: Anal. Calcd. for [M+H]⁺C₃₈H₄₇N₈O₄: 697.37. found 697.44.

Example 8

Example 8 (TFA salt) was prepared from carbamate 8d according to the procedure described for the synthesis of Example 1 (TFA salt) from carbamate 1e and by employing the appropriate acid. LC (Condition 3 & 4): >95% homogeneity index. LC/MS (Condition 1a): R_(t)=2.01 min. LC/MS: Anal. Calcd. for [M+H]⁺ C₄₂H₅₃N₁₀O₆: 793.41. found 793.39.

Example 9

Example 9 Step a

Bromide 9a was prepared starting from 2-bromo-1-(4-bromophenyl)ethanone and (1R,3S,5R)-2-methyl-2-azabicyclo[3.1.0]hexane-3-carboxylic acid (see patent application US20090068140 for its preparation) according to the procedure described for the synthesis of intermediate 1e. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.21/11.93 (two br s, 1H), 7.70-7.47 (m, 4.87H), 7.29 (d, J=1.6, 0.13H), 4.59 (br m, 1H), 3.41 (br m, 1H), 2.37-2.17 (br m, 2H), 1.62 (br m, 1H), 1.22 (very ‘br s’, 9H), 0.75 (m, 1H), 0.54 (m, 1H). LC/MS (Condition 1): R_(t)=1.87 min. LC/MS: Anal. Calcd. for [M+H]⁺C₁₉H₂₃ ⁸¹BrN₃O₂: 406.10. found 406.07.

Example 9 Step b

Carbamate 9a (4.13 g, 10.22 mmol) was dissolved in Dioxane (100 mL), and 4N HCl in dioxane (40 mL, 160 mmol) was added slowly and the reaction mixture was stirred at room temperature for 4 hr. All the volatile component was removed in vacuo to afford pyrrolidine 9b/2HCl as a yellow solid (3.8 g). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 10.38/9.94 (overlapping two ‘br s’, ˜2H), 7.92 (s, 1H), 7.78 (d, J=8.5, 2H), 7.63 (d, J=8.6, 2H), 4.68 (m, 1H), 3.39 (m, 1H), ˜2.5 (‘m’ partially overlapped with solvent signal, 2H), 1.91 (m, 1H), 1.11 (m, 1H), 0.83 (m, 1H). LC/MS (Condition 1): R_(t)=1.39 min. LC/MS: Anal. Calcd. for [M+H]⁺ C₁₄H₁₅ ⁷⁹BrN₃: 304.04. found 304.10.

Example 9 Step c

Benzylchloroformate (0.5 mL, 3.33 mmol) was added drop-wise over ˜1 min to a cooled (ice/water) mixture of pyrrolidine 9b/(2HCl) (1.05 g, 2.78 mmol), sodium carbonate (0.301 g, 2.84 mmol) in Dioxane (10 mL) and Water (10.00 mL) and the semi-heterogeneous mixture was stirred at the same temperature for 15 hr. Since LC/MS analysis indicated the presence of bis-Cbz side product in addition to the targeted product, NH₃/MeOH (2 N, 12 mL) was added and stirring was continued for 5 hr. The reaction mixture was concentrated to ⅓ of its volume, partitioned between CH₂Cl₂ (50 mL) and water (20 mL), and the organic layer was dried (MgSO₄) and evaporated in vacuo. The resultant crude material was purified with a Biotage (80 g silica gel; sample was loaded with CH₂Cl₂; 60-70% EtOAc/hexanes) to afford bromide 9c as an off-white foam (0.992 g). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.24/12.02 (two br s, 1H), 7.71 (d, J=8.3, 1.8H), 7.61-6.97 (br m, 8.2H), 5.15-4.89 (m, 2H), 4.80-4.72 (m, 1H), 3.48 (m, 1H), 2.44-2.26 (m, 2H), 1.68 (m, 1H), 0.85-0.80 (m, 1H), 0.62-0.59 (m, 1H). LC/MS (Condition 1): R_(t)=2.06 min. LC/MS: Anal. Calcd. for [M+H]⁺ C₂₂H₂₁ ⁸¹BrN₃O₂: 440.08. found 440.09.

Example 9 Step d

Pd(Ph₃P)₄ (0.105 g, 0.091 mmol) was added to a mixture of bromide 9c (0.988 g, 2.254 mmol), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane) (1.167 g, 4.60 mmol), potassium acetate (0.582 g, 5.93 mmol) and dioxane (19 mL) in a 75 mL pressure tube. Nitrogen was bubbled through the mixture for 1 min, the vessel was capped and heated with 80° C. oil bath for 15.3 hr. The yellow heterogeneous mixture was removed from the heating bath, the volatile component was removed in vacuo, and a silica gel mesh was prepared from the residue and purified with a Biotage (60-70% EtOAc/hexanes). The resultant material was dissolved in CH₂Cl₂ (60 mL), washed with water (20 mL, 2×), dried (MgSO₄) and evaporated in vacuo to afford boronate 9d as an off-white foam (898.4 mg). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.29 (br s, 0.14H), 12.03 (br s, 0.86H), 7.77 (d, J=8.1, 1.71H), 7.67-7.63 (m, 2.38H), 7.57 (s, 1H), 7.25 (br s, 5H), 5.11-4.91 (m, 2H), 4.81-4.73 (m, 1H), 3.48 (m, 1H), 2.37 (m, 2H), 1.69 (m, 1H), 1.30 (s, 12H), 0.86-0.81 (m, 1H), 0.62-0.58 (m, 1H). LC/MS (Condition 1): R_(t)=2.29 min. LC/MS: Anal. Calcd. for [M+H]⁺C₂₈H₃₃ ¹¹BN₃O₄: 486.26. found 486.24. [Note: a pinacol-hydrolyzed variant is also observed in the LC/MS at R_(t)=1.63 min].

Example 9 Step e

Pd(Ph₃P)₄ (0.023 g, 0.020 mmol) was added to a mixture of bromide 8c (0.1483 g, 0.364 mmol), boronate 9d (0.205 g, 0.422 mmol), and NaHCO₃ (0.105 g, 1.250 mmol) in 1,2-Dimethoxyethane (2.4 mL) and Water (0.8 mL), flushed with nitrogen and heated at 80° C. for 8 hr. Most of the volatile component was removed in vacuo and the residue was partitioned between CH₂Cl₂ (50 mL) and water (20 mL). The organic layer was dried (MgSO₄), concentrated in vacuo and purified with a Biotage (40 g silica gel; sample was loaded with CH₂Cl₂; eluted with 0-10% MeOH/EtOAc) to afford biphenyl 9e as light yellow film of solid, containing residual EtOAc in a 2.5/1.0 product/solvent ratio. Taking into consideration the residual solvent, the sample had an effective mass of 126 mg. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 12.34 (s, 0.18H), 12.24 (s, 0.17H), 11.99/11.89 (two overlapping ‘br s’, 1.65H), 7.90-7.53 (m, 10H), 7.25 (br m, 5H), 5.13-4.75 (m, 4H), 3.52-3.48 (m, 1H), 3.16-2.98 (m, 2H), 2.62 (s, 3H), 2.47-2.31 (m, 4H; partially overlapped with solvent signal), 1.70 (m, 1H), 1.30/1.27 (two overlapping s, 9H), 0.87-0.81 (m, 1H), 0.62 (m, 1H). LC/MS (Condition 1): R_(t)=1.99 min. LC/MS: Anal. Calcd. for [M+H]⁺C₄₀H₄₄N₂O₄: 686.35. found 686.42.

Example 9 Step f

A slurry of Pd/C (32.6 mg) in EtOH (1.0 mL) was added to a mixture of carbamate 9e (0.127 g, 0.185 mmol) and K₂CO₃ (0.0287 g, 0.208 mmol) in EtOH (2 ML), and stirred under a balloon of hydrogen for ˜5 hr. The reaction mixture was filtered through a pad of diatomaceous earth (Celite®), washed with MeOH and concentrated in vacuo to afford pyrrolidine 9f as a film of yellow solid. The sample weighed 117.2 mg (which is above the expected theoretical value, and likely an indication of the presence of either KHCO₃ or K₂CO₃). The material was submitted to the next step as such. LC/MS (Condition 1): R_(t)=1.67 min. LC/MS: Anal. Calcd. for [M+H]⁺C₃₂H₃₈N₇O₂: 552.31. found 552.30.

Example 9

Example 9 (TFA salt) was prepared from pyrrolidine 9f according to the following three-steps sequence: (i) Pyrrolidine 9f was coupled with (S)-2-(methoxycarbonylamino)-2-(tetrahydro-2H-pyran-4-yl)acetic acid by employing the procedure described for Example 1 with the exception that the purification of the crude material was conducted according to the procedure described for intermediate 1e, including the free-basing step; (ii) the deprotection of the Boc group was conducted according to the preparation of intermediate 1f; and, (iii) the resulting product was coupled with (S)-2-(methoxycarbonylamino)-3-methylbutanoic acid according to the procedure described for Example 1. ¹H NMR (DMSO-d₆ spiked with D₂O, δ=2.50 ppm, 400 MHz): 8.13-7.85 (m, 10H), 5.29 (m, 1H), 4.99 (m, 1H), 4.79-4.36 (overlapped ‘m’ & ‘d’, J=6.8 for ‘d’, 2H), 3.85-3.81 (m, 3H), 3.55 (s, 3H), 3.52 (s, 3H), 3.33-2.59 (overlapped ‘br m’ & s, ‘s’ is at 2.67, 9H), 2.56-2.25 (m, 2H), 2.12-2.04 (m, 2H), 1.97-1.89 (m, 1H), 1.48-1.32 (m, 4H), 0.98-0.68 (m, 8H). LC/MS (Condition 1a): R_(t)=1.80 min. LC/MS: Anal. Calcd. for [M+H]⁺C₄₃H₅₄N₉O₇: 808.41. found 808.46. LC (Condition 3 & 4): >95% homogeneity index.

Example 10

Example 10 Step a

A DMF (24 mL) solution of 1-benzyl 2-tert-butyl hydrazine-1,2-dicarboxylate (4.871 g, 18.29 mmol) was added drop-wise over 12 min to an ice-water cooled DMF (45 mL) suspension of NaH (1.63 g, 40.8 mmol). The resulting heterogeneous mixture was stirred for 15 min, and the cooling bath was removed and stirring was continued for 3.5 h. Then, 1,3-dibromopropane (2.5 mL, 24.48 mmol) was added drop-wise over 5 min to the above heterogeneous mixture, at which time a rigorous evolution of gas accompanied by the gradual homogenization of the reaction mixture, was observed. The mixture was stirred for ˜18.5 h, excess MeOH was added, and the volatile component was removed in vacuo. The residue was partitioned between CH₂Cl₂ (100 mL) and water (20 mL). The organic layer was washed with water (20 mL), dried (MgSO₄), concentrated in vacuo, and the resultant oil was submitted to a Biotage purification (300 g silica gel; 20-50% EtOAc/hexanes) to afford pyrazolidine 10a as a colorless oil (4.963 g). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 7.37-7.30 (m, 5H), 5.17 (br d, J=12.4, 1H), 5.07 (br d, J=12.1, 1H), 3.77 (m, 2H), 3.23-3.09 (m, 2H), 2.02-1.93 (m, 2H), 1.35 (s, 9H). LC/MS: Anal. Calcd. for [M+Na]⁺ C₁₆H₂₂N₂NaO₄: 329.15. found 329.23.

Example 10 Step b

A Dioxane (41 mL) solution of carbamate 10a (4.96 g, 16.19 mmol) was chilled with ice/water for ˜3 min, and HCl/dioxane (21 mL of 4.0 N, 84 mmol) was added over ˜2 min. The cooling bath was removed immediately after the end of addition and stirring was continued at ambient temperature for 16 h. Removal of the volatile component in vacuo afforded the HCl salt of pyrazolidine 10b as a white solid (3.848 g). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 7.45-7.33 (m, 5H), 5.21 (s, 2H), 3.62 (t, J=7.1, 2H), 3.37 (t, J=7.0, 2H), 2.21-2.14 (m, 2H). LC/MS: Anal. Calcd. for [M+Na]⁺C₁₁H₁₄N₂NaO₂: 229.10. found 229.12.

Example 10 Step c

Triethylamine (4.80 mL, 34.4 mmol) was added to a mixture of DMF (26 mL) and pyrazolidine 10b/HCl (2.353 g, 9.70 mmol) and stirred vigorously for 10 min, followed by a sonication for ˜1 min. The resultant heterogeneous mixture was cooled with ice/water bath and treated with 2,2,10,10-tetramethyl-6-thioxo-3,9-dioxa-5,7-diazaundecane-4,8-dione (2.815 g, 10.19 mmol), stirred for 5 min and then HgCl₂ (2.95 g, 10.87 mmol) was added in portions over 30 s. Stirring was continued for 5 h while allowing the bath to thaw to 10° C., and then the bath was removed and stirring was continued for 4 h. The reaction mixture was filtered through a pad of diatomaceous earth (Celite®) and the filtrate was concentrated in vacuo. The residue was dissolved in CH₂Cl₂ (100 mL) and was washed with water (40 mL, 2×), dried (MgSO₄) and concentrated in vacuo. The residue was submitted to a Biotage purification (300 g silica gel; 20-50% EtOAc/hexanes) to afford guanidine 10c as a white foam (3.924 g). Note that the E/Z stereochemistry of the product was not determined. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 9.61 (br s, 1H), 7.36-7.29 (m, 5H), 5.13 (s, 2H), 3.77 (very broad signal, 2H), 3.26 (very broad signal, 2H), 2.03-1.96 (m, 2H), 1.39/1.37 (two overlapping s, 18H). LC/MS: Anal. Calcd. for [M+Na]⁺ C₂₂H₃₂N₄NaO₆: 471.22. found 471.11.

Example 10 Step d

A THF (10 mL) solution of guanidine 10c (1.452 g, 3.24 mmol) was added drop-wise over 10 min to a THF (20 mL) suspension of NaH (0.14 g of 60% oil dispersion, 3.50 mmol) and the mixture was stirred for 10 min. A mixture of 2-bromo-1-(4-bromophenyl)ethanone (1.883 g, 6.77 mmol) and KI (0.051 g, 0.307 mmol) was added to the above mixture, and stirring of the semi-heterogeneous mixture was continued at ambient temperature for 4 h. The volatile component was removed in vacuo and the residue was partitioned between CH₂Cl₂ (100 mL), water (20 mL) and saturated NH₄Cl (2 mL). The organic layer was dried (MgSO₄), concentrated in vacuo and the resultant oil was submitted to a Biotage purification (300 g silica gel; sample was loaded with 20% EtOAc/hexanes; column elution with 20-50% EtOAc/hexanes) to afford ketone 10d (white foam, 0.910 g) and non-consumed starting material 10c (0.606 g). The E/Z stereochemistry of the product was not determined. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 7.85/7.76 (overlapping of br s & d, J=8.3, 4H), 7.42-7.30 (m, 5H), 5.20-4.38 (very broad m, 4H), 4.17-3.70 (very broad m, 2H), 3.30 (app br s, 2H), 2.13 (app br s, 2H), 1.33/1.28 (overlapping s, 18H). LC/MS: Anal. Calcd. for [M+H]⁺C₃₀H₃₈ ⁸¹BrN₄O₇: 647.19. found 647.25.

Example 10 Step e

25% TFA/CH₂Cl₂ (28 mL) was added to ketone 10d (1.846 g, 2.86 mmol) and stirred at room temperature for ˜21 h. Most of the dichloromethane was removed in vacuo and the residue was treated with MeOH (200 mL) and stirred for 28 h. Most of the volatile component was removed in vacuo and the residue was treated with CH₂Cl₂ (80 mL), water (20 mL) and saturated NaHCO₃ solution (10 mL), stirred vigorously for a few minutes and the phases were partitioned. The organic layer was dried (MgSO₄) and concentrated in vacuo and the crude material was purified with a Biotage (240 g silica gel; sample was loaded with 50% EtOAc/hexanes; column eluted with 50-80% EtOAc/hexanes) to afford imidazole 10e as a white foam (1.138 g). ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 11.60/11.53 (overlapping br s, 1H), 7.64-7.58 (m, 2H), 7.53-7.46 (m, 2H), 7.39-7.29 (m, 6H), 5.15 (s, 2H), 3.64/3.57 (overlapping m, 4H), 2.04-1.97 (m, 2H). LC/MS: Anal. Calcd. for [M+H]⁺ C₂₀H₂₀ ⁷⁹BrN₄O₂: 427.08. found 427.10.

Example 10 Step f

NaH (0.092 g of 60% oil dispersion, 2.30 mmol) was added in one batch to a cooled (ice/water) THF (12.5 mL) solution of imidazole 10e (0.918 g, 2.148 mmol) and stirred for 10 min. Then SEMCl (0.46 mL, 2.48 mmol) was added drop-wise over 1 min, and stirred at similar temperature for 25 min. The cooling bath was removed and stirring of the reaction mixture was continued for 65 min, and then MeOH (2 mL) was added and a few minutes later the volatile component was removed in vacuo. A silica gel mesh was prepared directly from the crude material and submitted to a Biotage purification (240 g silica gel; 10-20% EtOAc/hexanes) to afford bromide 10f as a colorless viscous oil (744 mg). Note that the regiochemistry of the SEM group on the imidazole ring was not determined, and was inconsequential for the current purpose. ¹H NMR (DMSO-d₆, δ=2.50 ppm, 400 MHz): 7.67-7.65 (m, 3H), 7.53 (d, J=8.3, 2H), 7.34-7.27 (m, 5H), 5.32 (s, 2H), 5.09 (s, 2H), 3.68 (app t, J=7.5, 2H), 3.51 (app t, J=8.1, 2H), 3.37 (app t, J=6.7, 2H), 2.32-2.25 (m, 2H), 0.82 (app t, J=8.1, 2H), −0.05 (s, 9H). LC/MS: Anal. Calcd. for [M+H]⁺ C₂₆H₃₄ ⁸¹BrN₄O₃Si: 559.16. found 559.04.

Example 10 Step g

A mixture of PdCl₂(dppf).CH₂Cl₂ (0.0473 g, 0.058 mmol) and dppf (0.0321 g, 0.058 mmol) was added to the mixture of bromide 10f (0.899 g, 1.61 mmol), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane) (0.218 g, 0.857 mmol) and K₂CO₃ (0.2391 g, 1.730 mmol) in DMSO (18 mL). Nitrogen was bubbled through the mixture for 10 min, and then it was heated with an oil bath (˜80° C.) for 23 h. After the reaction mixture was allowed to cool to room temperature, it was diluted with CH₂Cl₂ (60 mL) and washed with water (20 mL, 3×). The organic layer was dried (MgSO₄) and concentrated in vacuo. A silica gel mesh was prepared from the resulting crude residue and submitted to a Biotage purification (90 g silica gel; 10-40% EtOAc/hexanes) to afford coupled product 10 g as a light yellow foam (359 mg). Note that the regiochemistry of the SEM group on the imidazole ring was not determined. ¹H NMR (CDCl₃, δ=7.24 ppm, 400 MHz): 7.77 (d, J=8.3, 4H), 7.60 (d, J=8.6, 4H), 7.35-7.28 (m, 10H), 7.14 (s, 2H), 5.37 (br s, 4H), 5.14 (s, 4H), 3.81 (app t, J=3.5, 4H), 3.51 (app t, J=8.2, 4H), 3.45 (app t, J=7.0, 4H), 2.47 (m, 4H), 0.88 (app t, J=8.2, 4H), −0.03 (s, 18H). HRMS: Anal. Calcd. for [M+H]⁺ C₅₂H₆₇N₈O₆Si₂: 955.4717. found 955.4725.

Example 10

A 2:1 (v/v) mixture of TFA/CH₂Cl₂ (3 mL) was added to intermediate 10 g (52.2 mg, 0.055 mmol) and the stirred at room temperature for 19 h. The volatile component was removed in vacuo, and the residue was partitioned between CH₂Cl₂ (30 mL), water (10 mL) and saturated NaHCO₃ solution (1 mL). The organic layer was dried (MgSO₄), concentrated in vacuo, and the residue was dissolved in DMF and purified with a reverse phase HPLC (MeOH/H₂O/TFA) to afford the TFA salt of Example 10 as a white foam (16.2 mg). ¹H NMR (DMSO-d₆, δ=7.24 ppm, 400 MHz): 7.88 (d, J=9.1, 4H), 7.85 (d, J=8.8, 4H), 7.77 (s, 2H), 7.40-7.30 (m, 10H), 5.19 (s, 4H), 3.79 (app t, J=6.8, 4H), 3.71 (m, 4H), 2.19 (m, 4H). LC (Condition 2 & 3): >95% homogeneity index. LC/MS (Condition 1): R_(t)=2.09 min. LC/MS: Anal. Calcd. for [M+H]⁺C₄₀H₃₉N₈O₄: 695.31. found 695.35.

The free-base form of Example 10 could be obtained instead by employing the following purification protocol: after the aqueous work up, a silica gel mesh was prepared and submitted to a Biotage purification (silica gel; 30% CH₂Cl₂/EtOAc) to afford Example 10 as a light yellow solid.

Example 11

A solution of HCl in EtOH (0.1 mL of ˜2.5 M, 0.250 mmol) was added drop-wise over 20 s to a CH₂Cl₂ (2.5 mL) semi-suspension of the free-base form of Example 10 (59.2 mg, 0.085 mmol) and stirred for 10 min. A suspension of 10% Pd/C (0.012 g) in CH₂Cl₂ (0.5 mL) was added, followed by MeOH (1.0 mL), and the mixture was stirred under a balloon of hydrogen for 1.5 h. Additional HCl/EtOH (0.1 mL of 2.5 M, 0.250 mmol) was added and stirring was continued for 1.5 h. The mixture was filtered through a pad of Celite® with the assistance of excess methanol, the filtrate was concentrated, and the resultant material was exposed to high vacuum for 1.5 h and submitted to the next step without characterizations.

(S)-2-(methoxycarbonylamino)-3-methylbutanoic acid (0.0361 g, 0.206 mmol), DMF (2.5 mL) and DIEA (0.09 mL, 0.515 mmol) were added sequentially to the above crude product, and the resultant mixture was treated with HATU (0.067 g, 0.176 mmol) and stirred at room temperature for 4.3 h. The volatile component was removed in vacuo, and the residue was passed through an MCX column (1 g; MeOH wash; 2.0 M NH₃/MeOH elution) and the elute was concentrated in vacuo. The resultant material was dissolved in MeOH and purified with a reverse phase HPLC (MeOH/H₂O/TFA) to afford the TFA salt of Example 11 (40.5 mg) as an off-white foam. ¹H NMR (DMSO-d₆, δ=7.24 ppm, 400 MHz): 7.85 (app s, 8H), 7.74 (br s, 2H), 7.60 (very br m, 2H; exchangeable with D₂O), 4.25 (app br s, 2H), 4.13/3.98 (two overlapping app br s, 4H), 3.52 (s, 6H), 3.34 (app br s, 4H), 2.12 (app br s, 4H), 1.95 (app br s, 2H), 0.89-0.85 (m, 12H). LC (Condition 3 & 4): >95% homogeneity index. LC/MS (Condition 1): R_(t)=1.79 min. LC/MS: Anal. Calcd. for [M+H]⁺ C₃₈H₄₉N₁₀O₆: 741.38. found 741.48.

Example 12

Example 12 (TFA salt) was prepared according to the procedure described for Example 11 with the exception that (R)-2-(methoxycarbonylamino)-2-phenylacetic acid was employed in place of (S)-2-(methoxycarbonylamino)-3-methylbutanoic acid. LC (Condition 3 & 4): 95% homogeneity index. LC/MS (Condition 2): R_(t)=14.4 min. LC/MS: Anal. Calcd. for [M+H]⁺C₄₄H₄₅N₁₀O₆: 809.35. found 809.60.

Biological Activity

An HCV Replicon assay was utilized in the present disclosure, and was prepared, conducted and validated as described in commonly owned PCT/US2006/022197 and in O'Boyle et. al. Antimicrob Agents Chemother. 2005 April; 49(4):1346-53. Assay methods incorporating luciferase reporters have also been used as described (Apath.com).

HCV-neo replicon cells and replicon cells containing mutations in the NS5A region were used to test the currently described family of compounds. The compounds were determined to have more than 10-fold less inhibitory activity on cells containing mutations than wild-type cells. Thus, the compounds of the present disclosure can be effective in inhibiting the function of the HCV NS5A protein and are understood to be as effective in combinations as previously described in application PCT/US2006/022197 and commonly owned WO/04014852. Further, the compounds of the present disclosure can be effective against the HCV 1b genotype. It should also be understood that the compounds of the present disclosure can inhibit multiple genotypes of HCV. Table 2 shows the EC₅₀ (Effective 50% inhibitory concentration) values of representative compounds of the present disclosure against the HCV 1b genotype. In one embodiment, compounds of the present disclosure are inhibitory versus 1a, 1b, 2a, 2b, 3a, 4a, and 5a genotypes. EC₅₀ values against HCV 1b are as follows: A =>100 nM; B=1-99 nM; C=101-999 pM; and D=0.7-100 pM.

TABLE 2 1b EC₅₀ in 1b EC₅₀ Example μM in Range Name 1 0.000003 D methyl ((1S)-1-(((5S)-5-(5-(4′- (2-((3S)-2-((2S)-2- ((methoxycarbonyl)amino)-3- methylbutanoyl)-1-methyl-3- pyrazolidinyl)-1H-imidazol-5- yl)-4-biphenylyl)-1H-imidazol- 2-yl)-2-methyl-1- pyrazolidinyl)carbonyl)-2- methylpropyl)carbamate 2 D dimethyl (4,4′- biphenyldiylbis(1H-imidazole- 4,2-diyl((5S)-2-methyl-5,1- pyrazolidinediyl)((1S)-2-oxo-1- (tetrahydro-2H-pyran-4-yl)-2,1- ethanediyl)))biscarbamate 3 D dimethyl (4,4′- biphenyldiylbis(1H-imidazole- 5,2-diyl((5S)-2-methyl-5,1- pyrazolidinediyl)((2S)-1-oxo- 1,2-butanediyl)))biscarbamate 4 D methyl ((1R)-2-((5S)-5-(5-(4′- (2-((3S)-2-((2S)-2- ((methoxycarbonyl)amino)-2- phenylacetyl)-1-methyl-3- pyrazolidinyl)-1H-imidazol-5- yl)-4-biphenylyl)-1H-imidazol- 2-yl)-2-methyl-1- pyrazolidinyl)-2-oxo-1- phenylethyl)carbamate 5 D dimethyl (4,4′- biphenyldiylbis(1H-imidazole- 5,2-diyl((5S)-2-methyl-5,1- pyrazolidinediyl)((1R)-2-oxo- 1-phenyl-2,1- ethanediyl)))biscarbamate 6 D methyl ((1S)-1-(((5S)-5-(4-(4′- (2-((3S)-2-((2S)-2- ((methoxycarbonyl)amino)-2- (tetrahydro-2H-pyran-4- yl)acetyl)-1-methyl-3- pyrazolidinyl)-1H-imidazol-4- yl)-4-biphenylyl)-1H-imidazol- 2-yl)-2-methyl-1- pyrazolidinyl)carbonyl)-2- methylpropyl)carbamate 7 D dimethyl (4,4′- biphenyldiylbis((4-chloro-1H- imidazole-5,2-diyl)((5S)-2- methyl-5,1- pyrazolidinediyl)((2S)-1-oxo- 1,2-butanediyl)))biscarbamate 7.1 0.0000008 D methyl ((1S)-1-(((5S)-5-(4- chloro-5-(4′-(4-chloro-2-((3S)- 2-((2S)-2- ((methoxycarbonyl)amino)-3- methylbutanoyl)-1-methyl-3- pyrazolidinyl)-1H-imidazol-5- yl)-4-biphenylyl)-1H-imidazol- 2-yl)-2-methyl-1- pyrazolidinyl)carbonyl)-2- methylpropyl)carbamate 8 0.00020 C methyl ((1S)-1-(((5S)-5-(5-(4- ((4-(2-((3S)-2-((2S)-2- ((methoxycarbonyl)amino)-3- methylbutanoyl)-1-methyl-3- pyrazolidinyl)-1H-imidazol-5- yl)phenyl)ethynyl)phenyl)-1H- imidazol-2-yl)-2-methyl-1- pyrazolidinyl)carbonyl)-2- methylpropyl)carbamate 9 D methyl ((1S)-1-(((5S)-5-(5-(4′- (2-((1R,3S,5R)-2-((2S)-2- ((methoxycarbonyl)amino)-2- (tetrahydro-2H-pyran-4- yl)acetyl)-2- azabicyclo[3.1.0]hex-3-yl)-1H- imidazol-5-yl)-4-biphenylyl)- 1H-imidazol-2-yl)-2-methyl-1- pyrazolidinyl)carbonyl)-2- methylpropyl)carbamate 10 B dibenzyl 2,2′-(4,4′- biphenyldiylbis(1H-imidazole- 4,2-diyl))di(1- pyrazolidinecarboxylate) 11 <0.0137 ≦B methyl ((1S)-1-((2-(4-(4′-(2-(2- ((2S)-2- ((methoxycarbonyl)amino)-3- methylbutanoyl)-1- pyrazolidinyl)-1H-imidazol-4- yl)-4-biphenylyl)-1H-imidazol- 2-yl)-1- pyrazolidinyl)carbonyl)-2- methylpropyl)carbamate 12 C dimethyl (4,4′- biphenyldiylbis(1H-imidazole- 4,2-diyl-2,1- pyrazolidinediyl((1R)-2-oxo-1- phenyl-2,1- ethanediyl)))biscarbamate

It will be evident to one skilled in the art that the present disclosure is not limited to the foregoing illustrative examples, and that it can be embodied in other specific forms without departing from the essential attributes thereof. It is therefore desired that the examples be considered in all respects as illustrative and not restrictive, reference being made to the appended claims, rather than to the foregoing examples, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

The compounds of the present disclosure may inhibit HCV by mechanisms in addition to or other than NS5A inhibition. In one embodiment the compounds of the present disclosure inhibit HCV replicon and in another embodiment the compounds of the present disclosure inhibit NS5A. Compounds of the present disclosure may inhibit multiple genotypes of HCV. 

1. A compound of Formula (I)

or a pharmaceutically acceptable salt thereof, wherein L is selected from a bond,

R¹ and R² are

or R¹ is

and R² is selected from

wherein

denotes the point of attachment to the parent molecule; R³ and R⁴ are independently selected from hydrogen and halo; each R⁵ is independently selected from hydrogen and alkyl; each R⁶ is independently selected from hydrogen and alkyl; R^(6a) is hydrogen or alkyl, wherein the alkyl can optionally form a fused three-membered ring with an adjacent carbon atom; each R⁷ is independently selected from hydrogen and —C(O)R⁸; and each R⁸ is independently selected from alkoxy, alkyl, arylalkoxy, arylalkyl, cycloalkyl, heterocyclyl, heterocyclylalkyl, (NR^(c)R^(d))alkenyl, and (NR^(c)R^(d))alkyl.
 2. A compound of claim 1, or a pharmaceutically acceptable salt thereof, wherein L is a bond.
 3. A compound of claim 2, or a pharmaceutically acceptable salt thereof, wherein R¹ is

and R² is selected from


4. A compound of claim 3, or a pharmaceutically acceptable salt thereof, wherein R⁵ is hydrogen, R⁶ is methyl, and R^(6a) is alkyl, wherein the alkyl forms a fused three-membered ring with an adjacent carbon.
 5. A compound of claim 2, or a pharmaceutically acceptable salt thereof, wherein R¹ and R² are each


6. A compound of claim 1, or a pharmaceutically acceptable salt thereof, wherein L is


7. A compound of claim 6, or a pharmaceutically acceptable salt thereof, wherein R¹ and R² are each


8. A compound of claim 7, or a pharmaceutically acceptable salt thereof, wherein R⁵ is hydrogen and R⁶ is methyl.
 9. A compound selected from methyl ((1S)-1-(((5S)-5-(5-(4′-(2-((3S)-2-((2S)-2-((methoxycarbonyl)amino)-3-methylbutanoyl)-1-methyl-3-pyrazolidinyl)-1H-imidazol-5-yl)-4-biphenylyl)-1H-imidazol-2-yl)-2-methyl-1-pyrazolidinyl)carbonyl)-2-methylpropyl)carbamate; dimethyl (4,4′-biphenyldiylbis(1H-imidazole-4,2-diyl((5S)-2-methyl-5,1-pyrazolidinediyl)((1S)-2-oxo-1-(tetrahydro-2H-pyran-4-yl)-2,1-ethanediyl)))biscarbamate; dimethyl (4,4′-biphenyldiylbis(1H-imidazole-5,2-diyl((5S)-2-methyl-5,1-pyrazolidinediyl)((2S)-1-oxo-1,2-butanediyl)))biscarbamate; methyl ((1R)-2-((5S)-5-(5-(4′-(2-((3S)-2-((2S)-2-((methoxycarbonyl)amino)-2-phenylacetyl)-1-methyl-3-pyrazolidinyl)-1H-imidazol-5-yl)-4-biphenylyl)-1H-imidazol-2-yl)-2-methyl-1-pyrazolidinyl)-2-oxo-1-phenylethyl)carbamate; dimethyl (4,4′-biphenyldiylbis(1H-imidazole-5,2-diyl((5S)-2-methyl-5,1-pyrazolidinediyl)((1R)-2-oxo-1-phenyl-2,1-ethanediyl)))biscarbamate; methyl ((1S)-1-(5S)-5-(4-(4′-(2-((3S)-2-((2S)-2-((methoxycarbonyl)amino)-2-(tetrahydro-2H-pyran-4-yl)acetyl)-1-methyl-3-pyrazolidinyl)-1H-imidazol-4-yl)-4-biphenylyl)-1H-imidazol-2-yl)-2-methyl-1-pyrazolidinyl)carbonyl)-2-methylpropyl)carbamate; dimethyl (4,4′-biphenyldiylbis((4-chloro-1H-imidazole-5,2-diyl)((5S)-2-methyl-5,1-pyrazolidinediyl)((2S)-1-oxo-1,2-butanediyl)))biscarbamate; methyl ((1S)-1-(((5S)-5-(5-(4-((4-(2-((3S)-2-((2S)-2-((methoxycarbonyl)amino)-3-methylbutanoyl)-1-methyl-3-pyrazolidinyl)-1H-imidazol-5-yl)phenyl)ethynyl)phenyl)-1H-imidazol-2-yl)-2-methyl-1-pyrazolidinyl)carbonyl)-2-methylpropyl)carbamate; methyl ((1S)-1-(((5S)-5-(5-(4′-(2-((1R,3S,5R)-2-((2S)-2-((methoxycarbonyl)amino)-2-(tetrahydro-2H-pyran-4-yl)acetyl)-2-azabicyclo[3.1.0]hex-3-yl)-1H-imidazol-5-yl)-4-biphenylyl)-1H-imidazol-2-yl)-2-methyl-1-pyrazolidinyl)carbonyl)-2-methylpropyl)carbamate; dibenzyl 2,2′-(4,4′-biphenyldiylbis(1H-imidazole-4,2-diyl))di(1-pyrazolidinecarboxylate); methyl ((1S)-1-((2-(4-(4′-(2-(2-((2S)-2-((methoxycarbonyl)amino)-3-methylbutanoyl)-1-pyrazolidinyl)-1H-imidazol-4-yl)-4-biphenylyl)-1H-imidazol-2-yl)-1-pyrazolidinyl)carbonyl)-2-methylpropyl)carbamate; dimethyl (4,4′-biphenyldiylbis(1H-imidazole-4,2-diyl-2,1-pyrazolidinediyl((1R)-2-oxo-1-phenyl-2,1-ethanediyl)))biscarbamate; and, methyl ((1S)-1-(5S)-5-(4-chloro-5-(4′-(4-chloro-2-((3S)-2-(2S)-2-((methoxycarbonyl)amino)-3-methylbutanoyl)-1-methyl-3-pyrazolidinyl)-1H-imidazol-5-yl)-4-biphenylyl)-1H-imidazol-2-yl)-2-methyl-1-pyrazolidinyl)carbonyl)-2-methylpropyl)carbamate.
 10. A composition comprising a compound of claim 1, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.
 11. The composition of claim 10 further comprising one or two additional compounds having anti-HCV activity.
 12. The composition of claim 11 wherein at least one of the additional compounds is an interferon or a ribavirin.
 13. The composition of claim 12 wherein the interferon is selected from interferon alpha 2B, pegylated interferon alpha, consensus interferon, interferon alpha 2A, and lymphoblastoid interferon tau.
 14. The composition of claim 11 wherein at least one of the additional compounds is selected from interleukin 2, interleukin 6, interleukin 12, a compound that enhances the development of a type 1 helper T cell response, interfering RNA, anti-sense RNA, Imiqimod, ribavirin, an inosine 5′-monophosphate dehydrogenase inhibitor, amantadine, and rimantadine.
 15. The composition of claim 11 wherein at least one of the additional compounds is effective to inhibit the function of a target selected from HCV metalloprotease, HCV serine protease, HCV polymerase, HCV helicase, HCV NS4B protein, HCV entry, HCV assembly, HCV egress, HCV NS5A protein, and IMPDH for the treatment of an HCV infection.
 16. A method of treating an HCV infection in a patient, comprising administering to the patient a therapeutically effective amount of a compound of claim 1, or a pharmaceutically acceptable salt thereof.
 17. The method of claim 16 further comprising administering one or two additional compounds having anti-HCV activity prior to, after or simultaneously with the compound of claim 1, or a pharmaceutically acceptable salt thereof.
 18. The method of claim 17 wherein at least one of the additional compounds is an interferon or a ribavirin.
 19. The method of claim 18 wherein the interferon is selected from interferon alpha 2B, pegylated interferon alpha, consensus interferon, interferon alpha 2A, and lymphoblastoid interferon tau.
 20. The method of claim 17 wherein at least one of the additional compounds is selected from interleukin 2, interleukin 6, interleukin 12, a compound that enhances the development of a type 1 helper T cell response, interfering RNA, anti-sense RNA, Imiqimod, ribavirin, an inosine 5′-monophosphate dehydrogenase inhibitor, amantadine, and rimantadine.
 21. The method of claim 17 wherein at least one of the additional compounds is effective to inhibit the function of a target selected from HCV metalloprotease, HCV serine protease, HCV polymerase, HCV helicase, HCV NS4B protein, HCV entry, HCV assembly, HCV egress, HCV NS5A protein, and IMPDH for the treatment of an HCV infection. 